From: Murali Nalajala quic_mnalajal@quicinc.com
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@vger.kernel.org Signed-off-by: Murali Nalajala quic_mnalajal@quicinc.com Signed-off-by: Unnathi Chalicheemala quic_uchalich@quicinc.com Reviewed-by: Elliot Berman quic_eberman@quicinc.com --- 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@qui...
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));