firmware: qcom: scm: Mark get_wq_ctx() as atomic call

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>
Link: https://lore.kernel.org/r/20240814223244.40081-1-quic_uchalich@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
index dca5f3f1883bb4d574d203f183ff8198ea4322a7..2b4c2826f57251f25a1bc37c3b467dde28e1268b 100644 (file)
--- 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));