From: "Steven Rostedt (Google)" rostedt@goodmis.org

mainline inclusion from mainline-v6.2-rc1 commit 80b55772d41d8afec68dbc4ff0368a9fe5d1f390 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

A new "shutdown" timer state is being added to the generic timer code. One of the functions to change the timer into the state is called "timer_shutdown()". This means that there can not be other functions called "timer_shutdown()" as the timer code owns the "timer_*" name space.

Rename timer_shutdown() to spear_timer_shutdown() to avoid this conflict.

Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Acked-by: Arnd Bergmann arnd@arndb.de Acked-by: Viresh Kumar viresh.kumar@linaro.org Link: https://lkml.kernel.org/r/20221106212701.822440504@goodmis.org Link: https://lore.kernel.org/all/20221105060155.228348078@goodmis.org/ Link: https://lore.kernel.org/r/20221110064146.810953418@goodmis.org Link: https://lore.kernel.org/r/20221123201624.513863211@linutronix.de

Signed-off-by: Yu Liao liaoyu15@huawei.com --- arch/arm/mach-spear/time.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-spear/time.c b/arch/arm/mach-spear/time.c index d1fdb6066f7b..7b039f359338 100644 --- a/arch/arm/mach-spear/time.c +++ b/arch/arm/mach-spear/time.c @@ -93,7 +93,7 @@ static void __init spear_clocksource_init(void) 200, 16, clocksource_mmio_readw_up); }

-static inline void timer_shutdown(struct clock_event_device *evt) +static inline void spear_timer_shutdown(struct clock_event_device *evt) { u16 val = readw(gpt_base + CR(CLKEVT));

@@ -104,7 +104,7 @@ static inline void timer_shutdown(struct clock_event_device *evt)

static int spear_shutdown(struct clock_event_device *evt) { - timer_shutdown(evt); + spear_timer_shutdown(evt);

return 0; } @@ -114,7 +114,7 @@ static int spear_set_oneshot(struct clock_event_device *evt) u16 val;

/* stop the timer */ - timer_shutdown(evt); + spear_timer_shutdown(evt);

val = readw(gpt_base + CR(CLKEVT)); val |= CTRL_ONE_SHOT; @@ -129,7 +129,7 @@ static int spear_set_periodic(struct clock_event_device *evt) u16 val;

/* stop the timer */ - timer_shutdown(evt); + spear_timer_shutdown(evt);

period = clk_get_rate(gpt_clk) / HZ; period >>= CTRL_PRESCALER16;

From: "Steven Rostedt (Google)" rostedt@goodmis.org

mainline inclusion from mainline-v6.2-rc1 commit 6e1fc2591f116dfb20b65cf27356475461d61bd8 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

A new "shutdown" timer state is being added to the generic timer code. One of the functions to change the timer into the state is called "timer_shutdown()". This means that there can not be other functions called "timer_shutdown()" as the timer code owns the "timer_*" name space.

Rename timer_shutdown() to evt_timer_shutdown() to avoid this conflict.

Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lkml.kernel.org/r/20221106212702.182883323@goodmis.org Link: https://lore.kernel.org/all/20221105060155.592778858@goodmis.org/ Link: https://lore.kernel.org/r/20221110064147.158230501@goodmis.org Link: https://lore.kernel.org/r/20221123201624.634354813@linutronix.de

Signed-off-by: Yu Liao liaoyu15@huawei.com --- drivers/clocksource/timer-sp804.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/timer-sp804.c b/drivers/clocksource/timer-sp804.c index bedd3570474b..cf3e7c6f86c4 100644 --- a/drivers/clocksource/timer-sp804.c +++ b/drivers/clocksource/timer-sp804.c @@ -170,14 +170,14 @@ static irqreturn_t sp804_timer_interrupt(int irq, void *dev_id) return IRQ_HANDLED; }

-static inline void timer_shutdown(struct clock_event_device *evt) +static inline void evt_timer_shutdown(struct clock_event_device *evt) { writel(0, common_clkevt->ctrl); }

static int sp804_shutdown(struct clock_event_device *evt) { - timer_shutdown(evt); + evt_timer_shutdown(evt); return 0; }

@@ -186,7 +186,7 @@ static int sp804_set_periodic(struct clock_event_device *evt) unsigned long ctrl = TIMER_CTRL_32BIT | TIMER_CTRL_IE | TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;

- timer_shutdown(evt); + evt_timer_shutdown(evt); writel(common_clkevt->reload, common_clkevt->load); writel(ctrl, common_clkevt->ctrl); return 0;

From: Thomas Gleixner tglx@linutronix.de

mainline inclusion from mainline-v6.2-rc1 commit 9a5a305686971f4be10c6d7251c8348d74b3e014 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

del_singleshot_timer_sync() used to be an optimization for deleting timers which are not rearmed from the timer callback function.

This optimization turned out to be broken and got mapped to del_timer_sync() about 17 years ago.

Get rid of the undocumented indirection and use del_timer_sync() directly.

No functional change.

Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/r/20221123201624.706987932@linutronix.de

Conflicts: net/sunrpc/xprt.c Signed-off-by: Yu Liao liaoyu15@huawei.com --- drivers/char/tpm/tpm-dev-common.c | 4 ++-- drivers/misc/sgi-xp/xpc_partition.c | 2 +- drivers/staging/wlan-ng/hfa384x_usb.c | 4 ++-- drivers/staging/wlan-ng/prism2usb.c | 6 +++--- include/linux/timer.h | 2 -- kernel/time/timer.c | 2 +- net/sunrpc/xprt.c | 2 +- 7 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index b99e1941c52c..a9e7f5a82262 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -156,7 +156,7 @@ ssize_t tpm_common_read(struct file *file, char __user *buf, out: if (!priv->response_length) { *off = 0; - del_singleshot_timer_sync(&priv->user_read_timer); + del_timer_sync(&priv->user_read_timer); flush_work(&priv->timeout_work); } mutex_unlock(&priv->buffer_mutex); @@ -263,7 +263,7 @@ __poll_t tpm_common_poll(struct file *file, poll_table *wait) void tpm_common_release(struct file *file, struct file_priv *priv) { flush_work(&priv->async_work); - del_singleshot_timer_sync(&priv->user_read_timer); + del_timer_sync(&priv->user_read_timer); flush_work(&priv->timeout_work); file->private_data = NULL; priv->response_length = 0; diff --git a/drivers/misc/sgi-xp/xpc_partition.c b/drivers/misc/sgi-xp/xpc_partition.c index 57df06820bae..c56e10168d40 100644 --- a/drivers/misc/sgi-xp/xpc_partition.c +++ b/drivers/misc/sgi-xp/xpc_partition.c @@ -291,7 +291,7 @@ xpc_partition_disengaged(struct xpc_partition *part)

/* cancel the timer function, provided it's not us */ if (!in_interrupt()) - del_singleshot_timer_sync(&part->disengage_timer); + del_timer_sync(&part->disengage_timer);

DBUG_ON(part->act_state != XPC_P_AS_DEACTIVATING && part->act_state != XPC_P_AS_INACTIVE); diff --git a/drivers/staging/wlan-ng/hfa384x_usb.c b/drivers/staging/wlan-ng/hfa384x_usb.c index fac3f34d4a1f..9d4092f84c9b 100644 --- a/drivers/staging/wlan-ng/hfa384x_usb.c +++ b/drivers/staging/wlan-ng/hfa384x_usb.c @@ -1116,8 +1116,8 @@ static int hfa384x_usbctlx_complete_sync(struct hfa384x *hw, if (ctlx == get_active_ctlx(hw)) { spin_unlock_irqrestore(&hw->ctlxq.lock, flags);

- del_singleshot_timer_sync(&hw->reqtimer); - del_singleshot_timer_sync(&hw->resptimer); + del_timer_sync(&hw->reqtimer); + del_timer_sync(&hw->resptimer); hw->req_timer_done = 1; hw->resp_timer_done = 1; usb_kill_urb(&hw->ctlx_urb); diff --git a/drivers/staging/wlan-ng/prism2usb.c b/drivers/staging/wlan-ng/prism2usb.c index 4b08dc1da4f9..83fcb937a58e 100644 --- a/drivers/staging/wlan-ng/prism2usb.c +++ b/drivers/staging/wlan-ng/prism2usb.c @@ -171,9 +171,9 @@ static void prism2sta_disconnect_usb(struct usb_interface *interface) */ prism2sta_ifstate(wlandev, P80211ENUM_ifstate_disable);

- del_singleshot_timer_sync(&hw->throttle); - del_singleshot_timer_sync(&hw->reqtimer); - del_singleshot_timer_sync(&hw->resptimer); + del_timer_sync(&hw->throttle); + del_timer_sync(&hw->reqtimer); + del_timer_sync(&hw->resptimer);

/* Unlink all the URBs. This "removes the wheels" * from the entire CTLX handling mechanism. diff --git a/include/linux/timer.h b/include/linux/timer.h index d2dc1cb8b9f8..e7c9108f73a5 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -196,8 +196,6 @@ extern int try_to_del_timer_sync(struct timer_list *timer); # define del_timer_sync(t) del_timer(t) #endif

-#define del_singleshot_timer_sync(t) del_timer_sync(t) - extern void init_timers(void); extern void run_local_timers(void); struct hrtimer; diff --git a/kernel/time/timer.c b/kernel/time/timer.c index f7d3a108e27c..6987a4bb44cc 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1875,7 +1875,7 @@ signed long __sched schedule_timeout(signed long timeout) timer_setup_on_stack(&timer.timer, process_timeout, 0); __mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING); schedule(); - del_singleshot_timer_sync(&timer.timer); + del_timer_sync(&timer.timer);

/* Remove the timer from the object tracker */ destroy_timer_on_stack(&timer.timer); diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 9328fc1dbf1f..e9f43f80d563 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1143,7 +1143,7 @@ xprt_request_enqueue_receive(struct rpc_task *task) spin_unlock(&xprt->queue_lock);

/* Turn off autodisconnect */ - del_singleshot_timer_sync(&xprt->timer); + del_timer_sync(&xprt->timer); }

/**

From: Thomas Gleixner tglx@linutronix.de

mainline inclusion from mainline-v6.2-rc1 commit 14f043f1340bf30bc60af127bff39f55889fef26 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The kernel-doc of timer related functions is partially uncomprehensible word salad. Rewrite it to make it useful.

Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/r/20221123201624.828703870@linutronix.de

Signed-off-by: Yu Liao liaoyu15@huawei.com --- kernel/time/timer.c | 148 +++++++++++++++++++++++++++----------------- 1 file changed, 90 insertions(+), 58 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 6c8c9805a2fc..cbec76a98ac0 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1068,14 +1068,16 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option }

/** - * mod_timer_pending - modify a pending timer's timeout - * @timer: the pending timer to be modified - * @expires: new timeout in jiffies + * mod_timer_pending - Modify a pending timer's timeout + * @timer: The pending timer to be modified + * @expires: New absolute timeout in jiffies * - * mod_timer_pending() is the same for pending timers as mod_timer(), - * but will not re-activate and modify already deleted timers. + * mod_timer_pending() is the same for pending timers as mod_timer(), but + * will not activate inactive timers. * - * It is useful for unserialized use of timers. + * Return: + * * %0 - The timer was inactive and not modified + * * %1 - The timer was active and requeued to expire at @expires */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) { @@ -1084,24 +1086,27 @@ int mod_timer_pending(struct timer_list *timer, unsigned long expires) EXPORT_SYMBOL(mod_timer_pending);

/** - * mod_timer - modify a timer's timeout - * @timer: the timer to be modified - * @expires: new timeout in jiffies - * - * mod_timer() is a more efficient way to update the expire field of an - * active timer (if the timer is inactive it will be activated) + * mod_timer - Modify a timer's timeout + * @timer: The timer to be modified + * @expires: New absolute timeout in jiffies * * mod_timer(timer, expires) is equivalent to: * * del_timer(timer); timer->expires = expires; add_timer(timer); * + * mod_timer() is more efficient than the above open coded sequence. In + * case that the timer is inactive, the del_timer() part is a NOP. The + * timer is in any case activated with the new expiry time @expires. + * * Note that if there are multiple unserialized concurrent users of the * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * - * The function returns whether it has modified a pending timer or not. - * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an - * active timer returns 1.) + * Return: + * * %0 - The timer was inactive and started + * * %1 - The timer was active and requeued to expire at @expires or + * the timer was active and not modified because @expires did + * not change the effective expiry time */ int mod_timer(struct timer_list *timer, unsigned long expires) { @@ -1112,11 +1117,18 @@ EXPORT_SYMBOL(mod_timer); /** * timer_reduce - Modify a timer's timeout if it would reduce the timeout * @timer: The timer to be modified - * @expires: New timeout in jiffies + * @expires: New absolute timeout in jiffies * * timer_reduce() is very similar to mod_timer(), except that it will only - * modify a running timer if that would reduce the expiration time (it will - * start a timer that isn't running). + * modify an enqueued timer if that would reduce the expiration time. If + * @timer is not enqueued it starts the timer. + * + * Return: + * * %0 - The timer was inactive and started + * * %1 - The timer was active and requeued to expire at @expires or + * the timer was active and not modified because @expires + * did not change the effective expiry time such that the + * timer would expire earlier than already scheduled */ int timer_reduce(struct timer_list *timer, unsigned long expires) { @@ -1125,18 +1137,21 @@ int timer_reduce(struct timer_list *timer, unsigned long expires) EXPORT_SYMBOL(timer_reduce);

/** - * add_timer - start a timer - * @timer: the timer to be added + * add_timer - Start a timer + * @timer: The timer to be started * - * The kernel will do a ->function(@timer) callback from the - * timer interrupt at the ->expires point in the future. The - * current time is 'jiffies'. + * Start @timer to expire at @timer->expires in the future. @timer->expires + * is the absolute expiry time measured in 'jiffies'. When the timer expires + * timer->function(timer) will be invoked from soft interrupt context. * - * The timer's ->expires, ->function fields must be set prior calling this - * function. + * The @timer->expires and @timer->function fields must be set prior + * to calling this function. + * + * If @timer->expires is already in the past @timer will be queued to + * expire at the next timer tick. * - * Timers with an ->expires field in the past will be executed in the next - * timer tick. + * This can only operate on an inactive timer. Attempts to invoke this on + * an active timer are rejected with a warning. */ void add_timer(struct timer_list *timer) { @@ -1147,11 +1162,13 @@ void add_timer(struct timer_list *timer) EXPORT_SYMBOL(add_timer);

/** - * add_timer_on - start a timer on a particular CPU - * @timer: the timer to be added - * @cpu: the CPU to start it on + * add_timer_on - Start a timer on a particular CPU + * @timer: The timer to be started + * @cpu: The CPU to start it on + * + * Same as add_timer() except that it starts the timer on the given CPU. * - * This is not very scalable on SMP. Double adds are not possible. + * See add_timer() for further details. */ void add_timer_on(struct timer_list *timer, int cpu) { @@ -1187,15 +1204,18 @@ void add_timer_on(struct timer_list *timer, int cpu) EXPORT_SYMBOL_GPL(add_timer_on);

/** - * del_timer - deactivate a timer. - * @timer: the timer to be deactivated - * - * del_timer() deactivates a timer - this works on both active and inactive - * timers. - * - * The function returns whether it has deactivated a pending timer or not. - * (ie. del_timer() of an inactive timer returns 0, del_timer() of an - * active timer returns 1.) + * del_timer - Deactivate a timer. + * @timer: The timer to be deactivated + * + * The function only deactivates a pending timer, but contrary to + * del_timer_sync() it does not take into account whether the timer's + * callback function is concurrently executed on a different CPU or not. + * It neither prevents rearming of the timer. If @timer can be rearmed + * concurrently then the return value of this function is meaningless. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated */ int del_timer(struct timer_list *timer) { @@ -1217,10 +1237,19 @@ EXPORT_SYMBOL(del_timer);

/** * try_to_del_timer_sync - Try to deactivate a timer - * @timer: timer to delete + * @timer: Timer to deactivate + * + * This function tries to deactivate a timer. On success the timer is not + * queued and the timer callback function is not running on any CPU. * - * This function tries to deactivate a timer. Upon successful (ret >= 0) - * exit the timer is not queued and the handler is not running on any CPU. + * This function does not guarantee that the timer cannot be rearmed right + * after dropping the base lock. That needs to be prevented by the calling + * code if necessary. + * + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated + * * %-1 - The timer callback function is running on a different CPU */ int try_to_del_timer_sync(struct timer_list *timer) { @@ -1316,23 +1345,19 @@ static inline void del_timer_wait_running(struct timer_list *timer) { }

#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) /** - * del_timer_sync - deactivate a timer and wait for the handler to finish. - * @timer: the timer to be deactivated - * - * This function only differs from del_timer() on SMP: besides deactivating - * the timer it also makes sure the handler has finished executing on other - * CPUs. + * del_timer_sync - Deactivate a timer and wait for the handler to finish. + * @timer: The timer to be deactivated * * Synchronization rules: Callers must prevent restarting of the timer, * otherwise this function is meaningless. It must not be called from * interrupt contexts unless the timer is an irqsafe one. The caller must - * not hold locks which would prevent completion of the timer's - * handler. The timer's handler must not call add_timer_on(). Upon exit the - * timer is not queued and the handler is not running on any CPU. + * not hold locks which would prevent completion of the timer's callback + * function. The timer's handler must not call add_timer_on(). Upon exit + * the timer is not queued and the handler is not running on any CPU. * - * Note: For !irqsafe timers, you must not hold locks that are held in - * interrupt context while calling this function. Even if the lock has - * nothing to do with the timer in question. Here's why:: + * For !irqsafe timers, the caller must not hold locks that are held in + * interrupt context. Even if the lock has nothing to do with the timer in + * question. Here's why:: * * CPU0 CPU1 * ---- ---- @@ -1346,10 +1371,17 @@ static inline void del_timer_wait_running(struct timer_list *timer) { } * while (base->running_timer == mytimer); * * Now del_timer_sync() will never return and never release somelock. - * The interrupt on the other CPU is waiting to grab somelock but - * it has interrupted the softirq that CPU0 is waiting to finish. + * The interrupt on the other CPU is waiting to grab somelock but it has + * interrupted the softirq that CPU0 is waiting to finish. + * + * This function cannot guarantee that the timer is not rearmed again by + * some concurrent or preempting code, right after it dropped the base + * lock. If there is the possibility of a concurrent rearm then the return + * value of the function is meaningless. * - * The function returns whether it has deactivated a pending timer or not. + * Return: + * * %0 - The timer was not pending + * * %1 - The timer was pending and deactivated */ int del_timer_sync(struct timer_list *timer) {

From: Thomas Gleixner tglx@linutronix.de

mainline inclusion from mainline-v6.2-rc1 commit 9b13df3fb64ee95e2397585404e442afee2c7d4f category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The timer related functions do not have a strict timer_ prefixed namespace which is really annoying.

Rename del_timer_sync() to timer_delete_sync() and provide del_timer_sync() as a wrapper. Document that del_timer_sync() is not for new code.

Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Steven Rostedt (Google) rostedt@goodmis.org Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/r/20221123201624.954785441@linutronix.de

Signed-off-by: Yu Liao liaoyu15@huawei.com --- include/linux/timer.h | 15 ++++++++++++++- kernel/time/timer.c | 18 +++++++++--------- 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/include/linux/timer.h b/include/linux/timer.h index 6fcf2837e308..ef62727c4e70 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -189,7 +189,20 @@ extern int timer_reduce(struct timer_list *timer, unsigned long expires); extern void add_timer(struct timer_list *timer);

extern int try_to_del_timer_sync(struct timer_list *timer); -extern int del_timer_sync(struct timer_list *timer); +extern int timer_delete_sync(struct timer_list *timer); + +/** + * del_timer_sync - Delete a pending timer and wait for a running callback + * @timer: The timer to be deleted + * + * See timer_delete_sync() for detailed explanation. + * + * Do not use in new code. Use timer_delete_sync() instead. + */ +static inline int del_timer_sync(struct timer_list *timer) +{ + return timer_delete_sync(timer); +}

extern void init_timers(void); extern void run_local_timers(void); diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 46791b380802..7f4164c95abf 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1030,7 +1030,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option /* * We are trying to schedule the timer on the new base. * However we can't change timer's base while it is running, - * otherwise del_timer_sync() can't detect that the timer's + * otherwise timer_delete_sync() can't detect that the timer's * handler yet has not finished. This also guarantees that the * timer is serialized wrt itself. */ @@ -1208,7 +1208,7 @@ EXPORT_SYMBOL_GPL(add_timer_on); * @timer: The timer to be deactivated * * The function only deactivates a pending timer, but contrary to - * del_timer_sync() it does not take into account whether the timer's + * timer_delete_sync() it does not take into account whether the timer's * callback function is concurrently executed on a different CPU or not. * It neither prevents rearming of the timer. If @timer can be rearmed * concurrently then the return value of this function is meaningless. @@ -1344,7 +1344,7 @@ static inline void del_timer_wait_running(struct timer_list *timer) { } #endif

/** - * del_timer_sync - Deactivate a timer and wait for the handler to finish. + * timer_delete_sync - Deactivate a timer and wait for the handler to finish. * @timer: The timer to be deactivated * * Synchronization rules: Callers must prevent restarting of the timer, @@ -1366,10 +1366,10 @@ static inline void del_timer_wait_running(struct timer_list *timer) { } * spin_lock_irq(somelock); * <IRQ> * spin_lock(somelock); - * del_timer_sync(mytimer); + * timer_delete_sync(mytimer); * while (base->running_timer == mytimer); * - * Now del_timer_sync() will never return and never release somelock. + * Now timer_delete_sync() will never return and never release somelock. * The interrupt on the other CPU is waiting to grab somelock but it has * interrupted the softirq that CPU0 is waiting to finish. * @@ -1382,7 +1382,7 @@ static inline void del_timer_wait_running(struct timer_list *timer) { } * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -int del_timer_sync(struct timer_list *timer) +int timer_delete_sync(struct timer_list *timer) { int ret;

@@ -1415,7 +1415,7 @@ int del_timer_sync(struct timer_list *timer)

return ret; } -EXPORT_SYMBOL(del_timer_sync); +EXPORT_SYMBOL(timer_delete_sync);

static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *), @@ -1437,8 +1437,8 @@ static void call_timer_fn(struct timer_list *timer, #endif /* * Couple the lock chain with the lock chain at - * del_timer_sync() by acquiring the lock_map around the fn() - * call here and in del_timer_sync(). + * timer_delete_sync() by acquiring the lock_map around the fn() + * call here and in timer_delete_sync(). */ lock_map_acquire(&lockdep_map);

From: Thomas Gleixner tglx@linutronix.de

mainline inclusion from mainline-v6.2-rc1 commit d02e382cef06cc73561dd32dfdc171c00dcc416d category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers, is not trivial.

In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so is to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request.

In preparation for that replace the warnings in the relevant code paths with checks for timer->function == NULL. If the pointer is NULL, then discard the rearm request silently.

Add debug_assert_init() instead of the WARN_ON_ONCE(!timer->function) checks so that debug objects can warn about non-initialized timers.

The warning of debug objects does not warn if timer->function == NULL. It warns when timer was not initialized using timer_setup[_on_stack]() or via DEFINE_TIMER(). If developers fail to enable debug objects and then waste lots of time to figure out why their non-initialized timer is not firing, they deserve it. Same for initializing a timer with a NULL function.

Co-developed-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org Link: https://lore.kernel.org/r/87wn7kdann.ffs@tglx

Signed-off-by: Yu Liao liaoyu15@huawei.com --- kernel/time/timer.c | 57 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 76982f1244be..e732ae69da7f 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -964,7 +964,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option unsigned int idx = UINT_MAX; int ret = 0;

- BUG_ON(!timer->function); + debug_assert_init(timer);

/* * This is a common optimization triggered by the networking code - if @@ -991,6 +991,14 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option * dequeue/enqueue dance. */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base);

if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) && @@ -1017,6 +1025,14 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option } } else { base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated + * while holding base lock to prevent a race against the + * shutdown code. + */ + if (!timer->function) + goto out_unlock; + forward_timer_base(base); }

@@ -1075,8 +1091,12 @@ __mod_timer(struct timer_list *timer, unsigned long expires, unsigned int option * mod_timer_pending() is the same for pending timers as mod_timer(), but * will not activate inactive timers. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and not modified + * * %0 - The timer was inactive and not modified or was in + * shutdown state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) @@ -1102,8 +1122,12 @@ EXPORT_SYMBOL(mod_timer_pending); * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * + * If @timer->function == NULL then the start operation is silently + * discarded. In this case the return value is 0 and meaningless. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires did * not change the effective expiry time @@ -1123,8 +1147,12 @@ EXPORT_SYMBOL(mod_timer); * modify an enqueued timer if that would reduce the expiration time. If * @timer is not enqueued it starts the timer. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * Return: - * * %0 - The timer was inactive and started + * * %0 - The timer was inactive and started or was in shutdown + * state and the operation was discarded * * %1 - The timer was active and requeued to expire at @expires or * the timer was active and not modified because @expires * did not change the effective expiry time such that the @@ -1147,6 +1175,9 @@ EXPORT_SYMBOL(timer_reduce); * The @timer->expires and @timer->function fields must be set prior * to calling this function. * + * If @timer->function == NULL then the start operation is silently + * discarded. + * * If @timer->expires is already in the past @timer will be queued to * expire at the next timer tick. * @@ -1175,7 +1206,9 @@ void add_timer_on(struct timer_list *timer, int cpu) struct timer_base *new_base, *base; unsigned long flags;

- if (WARN_ON_ONCE(timer_pending(timer) || !timer->function)) + debug_assert_init(timer); + + if (WARN_ON_ONCE(timer_pending(timer))) return;

new_base = get_timer_cpu_base(timer->flags, cpu); @@ -1186,6 +1219,13 @@ void add_timer_on(struct timer_list *timer, int cpu) * wrong base locked. See lock_timer_base(). */ base = lock_timer_base(timer, &flags); + /* + * Has @timer been shutdown? This needs to be evaluated while + * holding base lock to prevent a race against the shutdown code. + */ + if (!timer->function) + goto out_unlock; + if (base != new_base) { timer->flags |= TIMER_MIGRATING;

@@ -1199,6 +1239,7 @@ void add_timer_on(struct timer_list *timer, int cpu)

debug_timer_activate(timer); internal_add_timer(base, timer); +out_unlock: raw_spin_unlock_irqrestore(&base->lock, flags); } EXPORT_SYMBOL_GPL(add_timer_on); @@ -1481,6 +1522,12 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)

fn = timer->function;

+ if (WARN_ON_ONCE(!fn)) { + /* Should never happen. Emphasis on should! */ + base->running_timer = NULL; + continue; + } + if (timer->flags & TIMER_IRQSAFE) { raw_spin_unlock(&base->lock); call_timer_fn(timer, fn, baseclk);

From: Thomas Gleixner tglx@linutronix.de

mainline inclusion from mainline-v6.2-rc1 commit 0cc04e80458a822300b93f82ed861a513edde194 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers, is not trivial.

In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so is to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request.

Add a shutdown argument to the relevant internal functions which makes the actual deactivation code set timer->function to NULL which in turn prevents rearming of the timer.

Co-developed-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org Link: https://lore.kernel.org/r/20221123201625.253883224@linutronix.de

Signed-off-by: Yu Liao liaoyu15@huawei.com --- kernel/time/timer.c | 62 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 54 insertions(+), 8 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 55b90df70b00..9901ae10b31a 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1247,12 +1247,19 @@ EXPORT_SYMBOL_GPL(add_timer_on); /** * __timer_delete - Internal function: Deactivate a timer * @timer: The timer to be deactivated + * @shutdown: If true, this indicates that the timer is about to be + * shutdown permanently. + * + * If @shutdown is true then @timer->function is set to NULL under the + * timer base lock which prevents further rearming of the time. In that + * case any attempt to rearm @timer after this function returns will be + * silently ignored. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -static int __timer_delete(struct timer_list *timer) +static int __timer_delete(struct timer_list *timer, bool shutdown) { struct timer_base *base; unsigned long flags; @@ -1260,9 +1267,22 @@ static int __timer_delete(struct timer_list *timer)

debug_assert_init(timer);

- if (timer_pending(timer)) { + /* + * If @shutdown is set then the lock has to be taken whether the + * timer is pending or not to protect against a concurrent rearm + * which might hit between the lockless pending check and the lock + * aquisition. By taking the lock it is ensured that such a newly + * enqueued timer is dequeued and cannot end up with + * timer->function == NULL in the expiry code. + * + * If timer->function is currently executed, then this makes sure + * that the callback cannot requeue the timer. + */ + if (timer_pending(timer) || shutdown) { base = lock_timer_base(timer, &flags); ret = detach_if_pending(timer, base, true); + if (shutdown) + timer->function = NULL; raw_spin_unlock_irqrestore(&base->lock, flags); }

@@ -1285,20 +1305,31 @@ static int __timer_delete(struct timer_list *timer) */ int timer_delete(struct timer_list *timer) { - return __timer_delete(timer); + return __timer_delete(timer, false); } EXPORT_SYMBOL(timer_delete);

/** * __try_to_del_timer_sync - Internal function: Try to deactivate a timer * @timer: Timer to deactivate + * @shutdown: If true, this indicates that the timer is about to be + * shutdown permanently. + * + * If @shutdown is true then @timer->function is set to NULL under the + * timer base lock which prevents further rearming of the timer. Any + * attempt to rearm @timer after this function returns will be silently + * ignored. + * + * This function cannot guarantee that the timer cannot be rearmed + * right after dropping the base lock if @shutdown is false. That + * needs to be prevented by the calling code if necessary. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated * * %-1 - The timer callback function is running on a different CPU */ -static int __try_to_del_timer_sync(struct timer_list *timer) +static int __try_to_del_timer_sync(struct timer_list *timer, bool shutdown) { struct timer_base *base; unsigned long flags; @@ -1310,6 +1341,8 @@ static int __try_to_del_timer_sync(struct timer_list *timer)

if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); + if (shutdown) + timer->function = NULL;

raw_spin_unlock_irqrestore(&base->lock, flags);

@@ -1334,7 +1367,7 @@ static int __try_to_del_timer_sync(struct timer_list *timer) */ int try_to_del_timer_sync(struct timer_list *timer) { - return __try_to_del_timer_sync(timer); + return __try_to_del_timer_sync(timer, false); } EXPORT_SYMBOL(try_to_del_timer_sync);

@@ -1415,12 +1448,25 @@ static inline void del_timer_wait_running(struct timer_list *timer) { } * __timer_delete_sync - Internal function: Deactivate a timer and wait * for the handler to finish. * @timer: The timer to be deactivated + * @shutdown: If true, @timer->function will be set to NULL under the + * timer base lock which prevents rearming of @timer + * + * If @shutdown is not set the timer can be rearmed later. If the timer can + * be rearmed concurrently, i.e. after dropping the base lock then the + * return value is meaningless. + * + * If @shutdown is set then @timer->function is set to NULL under timer + * base lock which prevents rearming of the timer. Any attempt to rearm + * a shutdown timer is silently ignored. + * + * If the timer should be reused after shutdown it has to be initialized + * again. * * Return: * * %0 - The timer was not pending * * %1 - The timer was pending and deactivated */ -static int __timer_delete_sync(struct timer_list *timer) +static int __timer_delete_sync(struct timer_list *timer, bool shutdown) { int ret;

@@ -1443,7 +1489,7 @@ static int __timer_delete_sync(struct timer_list *timer) WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));

do { - ret = __try_to_del_timer_sync(timer); + ret = __try_to_del_timer_sync(timer, shutdown);

if (unlikely(ret < 0)) { del_timer_wait_running(timer); @@ -1495,7 +1541,7 @@ static int __timer_delete_sync(struct timer_list *timer) */ int timer_delete_sync(struct timer_list *timer) { - return __timer_delete_sync(timer); + return __timer_delete_sync(timer, false); } EXPORT_SYMBOL(timer_delete_sync);

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG

--------------------------------

A previous commit made del_timer[_sync]() obsolete and unexported, which caused kabi to break. So making del_timer[_sync]() exported, the same as before.

Signed-off-by: Yu Liao liaoyu15@huawei.com --- include/linux/timer.h | 28 ++-------------------------- kernel/time/timer.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/include/linux/timer.h b/include/linux/timer.h index e095f11cf665..13fc6e688c73 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -190,35 +190,11 @@ extern void add_timer(struct timer_list *timer); extern int try_to_del_timer_sync(struct timer_list *timer); extern int timer_delete_sync(struct timer_list *timer); extern int timer_delete(struct timer_list *timer); +extern int del_timer_sync(struct timer_list *timer); +extern int del_timer(struct timer_list *timer); extern int timer_shutdown_sync(struct timer_list *timer); extern int timer_shutdown(struct timer_list *timer);

-/** - * del_timer_sync - Delete a pending timer and wait for a running callback - * @timer: The timer to be deleted - * - * See timer_delete_sync() for detailed explanation. - * - * Do not use in new code. Use timer_delete_sync() instead. - */ -static inline int del_timer_sync(struct timer_list *timer) -{ - return timer_delete_sync(timer); -} - -/** - * del_timer - Delete a pending timer - * @timer: The timer to be deleted - * - * See timer_delete() for detailed explanation. - * - * Do not use in new code. Use timer_delete() instead. - */ -static inline int del_timer(struct timer_list *timer) -{ - return timer_delete(timer); -} - extern void init_timers(void); extern void run_local_timers(void); struct hrtimer; diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 14c48a0144ea..c1b52dab3951 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1309,6 +1309,20 @@ int timer_delete(struct timer_list *timer) } EXPORT_SYMBOL(timer_delete);

+/** + * del_timer - Delete a pending timer + * @timer: The timer to be deleted + * + * See timer_delete() for detailed explanation. + * + * Do not use in new code. Use timer_delete() instead. + */ +int del_timer(struct timer_list *timer) +{ + return __timer_delete(timer, false); +} +EXPORT_SYMBOL(del_timer); + /** * timer_shutdown - Deactivate a timer and prevent rearming * @timer: The timer to be deactivated @@ -1569,6 +1583,20 @@ int timer_delete_sync(struct timer_list *timer) } EXPORT_SYMBOL(timer_delete_sync);

+/** + * del_timer_sync - Delete a pending timer and wait for a running callback + * @timer: The timer to be deleted + * + * See timer_delete_sync() for detailed explanation. + * + * Do not use in new code. Use timer_delete_sync() instead. + */ +int del_timer_sync(struct timer_list *timer) +{ + return __timer_delete_sync(timer, false); +} +EXPORT_SYMBOL(del_timer_sync); + /** * timer_shutdown_sync - Shutdown a timer and prevent rearming * @timer: The timer to be shutdown