From: Murali Nalajala <quic_mnalajal@xxxxxxxxxxx>
Currently get_wq_ctx() is wrongly configured as a standard call. When two
SMC calls are in sleep and one SMC wakes up, it calls get_wq_ctx() to
resume the corresponding sleeping thread. But if get_wq_ctx() is
interrupted, goes to sleep and another SMC call is waiting to be allocated
a waitq context, it leads to a deadlock.
To avoid this get_wq_ctx() must be an atomic call and can't be a standard
SMC call. Hence mark get_wq_ctx() as a fast call.
Fixes: 6bf325992236 ("firmware: qcom: scm: Add wait-queue handling logic")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Murali Nalajala <quic_mnalajal@xxxxxxxxxxx>
Signed-off-by: Unnathi Chalicheemala <quic_uchalich@xxxxxxxxxxx>
Reviewed-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
Changes in v2:
- Made commit message more clear.
- R-b tag from Elliot.
- Link to v1: https://lore.kernel.org/all/20240611-get_wq_ctx_atomic-v1-1-9189a0a7d1ba@xxxxxxxxxxx/
drivers/firmware/qcom/qcom_scm-smc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
index dca5f3f1883b..2b4c2826f572 100644
--- a/drivers/firmware/qcom/qcom_scm-smc.c
+++ b/drivers/firmware/qcom/qcom_scm-smc.c
@@ -73,7 +73,7 @@ int scm_get_wq_ctx(u32 *wq_ctx, u32 *flags, u32 *more_pending)
struct arm_smccc_res get_wq_res;
struct arm_smccc_args get_wq_ctx = {0};
- get_wq_ctx.args[0] = ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL,
+ get_wq_ctx.args[0] = ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,
ARM_SMCCC_SMC_64, ARM_SMCCC_OWNER_SIP,
SCM_SMC_FNID(QCOM_SCM_SVC_WAITQ, QCOM_SCM_WAITQ_GET_WQ_CTX));
--
2.34.1
