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: 6bf3259 ("firmware: qcom: scm: Add wait-queue handling logic")
Cc: [email protected]
Signed-off-by: Murali Nalajala <[email protected]>
Signed-off-by: Unnathi Chalicheemala <[email protected]>
Reviewed-by: Elliot Berman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Bjorn Andersson <[email protected]>

Author: Murali Nalajala

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));