From: James Clark james.clark@arm.com

mainline inclusion from mainline-v6.4-rc1 commit c45b2835e7b205783bdfe08cc98fa86a7c5eeb74 category: Bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I89FF2 CVE: NA

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

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child_fwnode should be a read only property based on the DT or ACPI. If it's cleared on the parent device when a child is unloaded, then when the child is loaded again the connection won't be remade.

child_dev should be cleared instead which signifies that the connection should be remade when the child_fwnode registers a new coresight_device.

Similarly the reference count shouldn't be decremented as long as the parent device exists. The correct place to drop the reference is in coresight_release_platform_data() which is already done.

Reproducible on Juno with the following steps:

# load all coresight modules. $ cd /sys/bus/coresight/devices/ $ echo 1 > tmc_etr0/enable_sink $ echo 1 > etm0/enable_source # Works fine ^

$ echo 0 > etm0/enable_source $ rmmod coresight-funnel $ modprobe coresight-funnel $ echo 1 > etm0/enable_source -bash: echo: write error: Invalid argument

Fixes: 37ea1ffddffa ("coresight: Use fwnode handle instead of device names") Fixes: 2af89ebacf29 ("coresight: Clear the connection field properly") Tested-by: Suzuki K Poulose suzuki.poulose@arm.com Reviewed-by: Mike Leach mike.leach@linaro.org Signed-off-by: James Clark james.clark@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Link: https://lore.kernel.org/r/20230425143542.2305069-2-james.clark@arm.com Signed-off-by: Junhao He hejunhao3@huawei.com --- drivers/hwtracing/coresight/coresight-core.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index ee7b5cfcf786..9696f402a328 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1443,13 +1443,8 @@ static int coresight_remove_match(struct device *dev, void *data) if (csdev->dev.fwnode == conn->child_fwnode) { iterator->orphan = true; coresight_remove_links(iterator, conn); - /* - * Drop the reference to the handle for the remote - * device acquired in parsing the connections from - * platform data. - */ - fwnode_handle_put(conn->child_fwnode); - conn->child_fwnode = NULL; + + conn->child_dev = NULL; /* No need to continue */ break; }