[PATCH v3 2/5] HID: amd_sfh: Serialize access to the shared emp2 pointer
From: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Date: 2026-08-03 17:53:12
Subsystem:
amd sensor fusion hub driver, hid core layer, the rest · Maintainers:
Basavaraj Natikar, Jiri Kosina, Benjamin Tissoires, Linus Torvalds
The SFH accessors reach the device through a file-global emp2 pointer that is published at probe and cleared on remove. amd_get_sfh_info() is exported and called from other modules on unrelated threads, so a reader can observe a non-NULL emp2 and then race a concurrent unbind that clears it and frees the device. Serialize the emp2 publish/clear and all readers under a mutex, so a reader either sees a live device for the whole access or sees NULL. Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com> --- drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c b/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c
index 837d59e7a661..dd2720bae65c 100644
--- a/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c
+++ b/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c@@ -8,12 +8,14 @@ * Author: Basavaraj Natikar <Basavaraj.Natikar@amd.com> */ #include <linux/amd-pmf-io.h> +#include <linux/cleanup.h> #include <linux/io-64-nonatomic-lo-hi.h> #include <linux/iopoll.h> #include "amd_sfh_interface.h" static struct amd_mp2_dev *emp2; +static DEFINE_MUTEX(emp2_lock); static int amd_sfh_wait_response(struct amd_mp2_dev *mp2, u8 sid, u32 cmd_id) {
@@ -78,12 +80,14 @@ static struct amd_mp2_ops amd_sfh_ops = { void sfh_deinit_emp2(void) { + guard(mutex)(&emp2_lock); emp2 = NULL; } void sfh_interface_init(struct amd_mp2_dev *mp2) { mp2->mp2_ops = &amd_sfh_ops; + guard(mutex)(&emp2_lock); emp2 = mp2; }
@@ -160,6 +164,8 @@ static int amd_sfh_als_info(u32 *ambient_light) int amd_get_sfh_info(struct amd_sfh_info *sfh_info, enum sfh_message_type op) { + guard(mutex)(&emp2_lock); + if (sfh_info) { switch (op) { case MT_HPD:
--
2.34.1