Hi Geert,

FYI, the error/warning still remains.

tree: https://gitee.com/openeuler/kernel.git openEuler-1.0-LTS head: d2a40c79ddef4b96b8a7a396bd7273121b1b4a5c commit: 9dae7e237a64858407b7626260bad53aa13c9198 [2662/23859] serial: sh-sci: Fix locking in sci_submit_rx() config: arm64-randconfig-002-20241026 (https://download.01.org/0day-ci/archive/20241026/202410260911.Qmhlx5mF-lkp@i...) compiler: aarch64-linux-gcc (GCC) 14.1.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241026/202410260911.Qmhlx5mF-lkp@i...)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202410260911.Qmhlx5mF-lkp@intel.com/

Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

In file included from include/linux/irqflags.h:16, from include/linux/spinlock.h:54, from include/linux/rwsem.h:16, from include/linux/notifier.h:15, from include/linux/clk.h:17, from drivers/tty/serial/sh-sci.c:24: In function 'arch_local_irq_restore', inlined from '__raw_spin_unlock_irqrestore' at include/linux/spinlock_api_smp.h:160:2, inlined from 'spin_unlock_irqrestore' at include/linux/spinlock.h:384:2, inlined from 'sci_submit_rx' at drivers/tty/serial/sh-sci.c:1376:3:

...

arch/arm64/include/asm/irqflags.h:88:9: warning: 'flags' may be used uninitialized [-Wmaybe-uninitialized]

88 | asm volatile( | ^~~ drivers/tty/serial/sh-sci.c: In function 'sci_submit_rx': drivers/tty/serial/sh-sci.c:1338:23: note: 'flags' was declared here 1338 | unsigned long flags; | ^~~~~ In file included from drivers/tty/serial/sh-sci.c:53: In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:940:7: include/linux/tty_flip.h:27:53: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 27 | *flag_buf_ptr(tb, tb->used) = flag; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ In file included from include/linux/serial_core.h:29, from include/linux/serial_sci.h:6, from drivers/tty/serial/sh-sci.c:46: include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:940:7: include/linux/tty_flip.h:28:47: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 28 | *char_buf_ptr(tb, tb->used++) = ch; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:950:7: include/linux/tty_flip.h:27:53: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 27 | *flag_buf_ptr(tb, tb->used) = flag; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:950:7: include/linux/tty_flip.h:28:47: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 28 | *char_buf_ptr(tb, tb->used++) = ch; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:960:7: include/linux/tty_flip.h:27:53: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 27 | *flag_buf_ptr(tb, tb->used) = flag; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_handle_errors' at drivers/tty/serial/sh-sci.c:960:7: include/linux/tty_flip.h:28:47: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 28 | *char_buf_ptr(tb, tb->used++) = ch; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ include/linux/tty.h: In function 'sci_handle_errors': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_receive_chars' at drivers/tty/serial/sh-sci.c:906:5: include/linux/tty_flip.h:27:53: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 27 | *flag_buf_ptr(tb, tb->used) = flag; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ include/linux/tty.h: In function 'sci_receive_chars': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_receive_chars' at drivers/tty/serial/sh-sci.c:906:5: include/linux/tty_flip.h:28:47: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 28 | *char_buf_ptr(tb, tb->used++) = ch; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ include/linux/tty.h: In function 'sci_receive_chars': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_receive_chars' at drivers/tty/serial/sh-sci.c:883:5: include/linux/tty_flip.h:27:53: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 27 | *flag_buf_ptr(tb, tb->used) = flag; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ include/linux/tty.h: In function 'sci_receive_chars': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~ In function 'tty_insert_flip_char', inlined from 'sci_receive_chars' at drivers/tty/serial/sh-sci.c:883:5: include/linux/tty_flip.h:28:47: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 28 | *char_buf_ptr(tb, tb->used++) = ch; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ include/linux/tty.h: In function 'sci_receive_chars': include/linux/tty.h:69:23: note: destination object 'data' of size 0 69 | unsigned long data[0]; | ^~~~

vim +/flags +88 arch/arm64/include/asm/irqflags.h

fb9bd7d6df81dd Marc Zyngier 2012-03-05 82 fb9bd7d6df81dd Marc Zyngier 2012-03-05 83 /* fb9bd7d6df81dd Marc Zyngier 2012-03-05 84 * restore saved IRQ state fb9bd7d6df81dd Marc Zyngier 2012-03-05 85 */ fb9bd7d6df81dd Marc Zyngier 2012-03-05 86 static inline void arch_local_irq_restore(unsigned long flags) fb9bd7d6df81dd Marc Zyngier 2012-03-05 87 { fb9bd7d6df81dd Marc Zyngier 2012-03-05 @88 asm volatile( fb9bd7d6df81dd Marc Zyngier 2012-03-05 89 "msr daif, %0 // arch_local_irq_restore" fb9bd7d6df81dd Marc Zyngier 2012-03-05 90 : fb9bd7d6df81dd Marc Zyngier 2012-03-05 91 : "r" (flags) fb9bd7d6df81dd Marc Zyngier 2012-03-05 92 : "memory"); fb9bd7d6df81dd Marc Zyngier 2012-03-05 93 } fb9bd7d6df81dd Marc Zyngier 2012-03-05 94

:::::: The code at line 88 was first introduced by commit :::::: fb9bd7d6df81ddf1e7ab6648ac89ddbe0625b26b arm64: IRQ handling

:::::: TO: Marc Zyngier marc.zyngier@arm.com :::::: CC: Catalin Marinas catalin.marinas@arm.com