On Thu, Jun 27, 2024 at 10:29:05AM -0700, Unnathi Chalicheemala wrote:
> 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>
> ---
> 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 16cf88acfa8e..0a2a2c794d0e 100644
> --- a/drivers/firmware/qcom/qcom_scm-smc.c
> +++ b/drivers/firmware/qcom/qcom_scm-smc.c
> @@ -71,7 +71,7 @@ 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
>
