Smatch caught that cxl_cper_post_event() is called with a spinlock held or preemption disabled.[1] There is no need for the callback to sleep. Replace the RW semaphore with a RW lock. A static call was considered but ARM does not select HAVE_STATIC_CALL and in that case setting the function pointer uses a RW semaphore. [1] https://lore.kernel.org/all/b963c490-2c13-4b79-bbe7-34c6568423c7@moroto.mountain/ Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> --- drivers/acpi/apei/ghes.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 7b7c605166e0..bdc0ec2813a3 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -39,6 +39,7 @@ #include <linux/aer.h> #include <linux/nmi.h> #include <linux/sched/clock.h> +#include <linux/spinlock.h> #include <linux/uuid.h> #include <linux/ras.h> #include <linux/task_work.h> @@ -677,7 +678,7 @@ static void ghes_defer_non_standard_event(struct acpi_hest_generic_data *gdata, /* * Only a single callback can be registered for CXL CPER events. */ -static DECLARE_RWSEM(cxl_cper_rw_sem); +static DEFINE_RWLOCK(cxl_callback_lock); static cxl_cper_callback cper_callback; /* CXL Event record UUIDs are formatted as GUIDs and reported in section type */ @@ -721,14 +722,14 @@ static void cxl_cper_post_event(enum cxl_event_type event_type, return; } - guard(rwsem_read)(&cxl_cper_rw_sem); + guard(read_lock_irqsave)(&cxl_callback_lock); if (cper_callback) cper_callback(event_type, rec); } int cxl_cper_register_callback(cxl_cper_callback callback) { - guard(rwsem_write)(&cxl_cper_rw_sem); + guard(write_lock_irq)(&cxl_callback_lock); if (cper_callback) return -EINVAL; cper_callback = callback; @@ -738,7 +739,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_cper_register_callback, CXL); int cxl_cper_unregister_callback(cxl_cper_callback callback) { - guard(rwsem_write)(&cxl_cper_rw_sem); + guard(write_lock_irq)(&cxl_callback_lock); if (callback != cper_callback) return -EINVAL; cper_callback = NULL; --- base-commit: 861c0981648f5b64c86fd028ee622096eb7af05a change-id: 20240201-cxl-cper-smatch-82b129498498 Best regards, -- Ira Weiny <ira.weiny@xxxxxxxxx>
