Commit c23c03bf authored by Cristian Marussi's avatar Cristian Marussi Committed by Sudeep Holla
Browse files

firmware: arm_scmi: Fix timeout checks on polling path 



Polling mode transactions wait for a reply busy-looping without holding a
spinlock, but currently the timeout checks are based only on elapsed time:
as a result we could hit a false positive whenever our busy-looping thread
is pre-empted and scheduled out for a time greater than the polling
timeout.

Change the checks at the end of the busy-loop to make sure that the polling
wasn't indeed successful or an out-of-order reply caused the polling to be
forcibly terminated.

Fixes: 31d2f803 ("firmware: arm_scmi: Add sync_cmds_completed_on_ret transport flag")
Reported-by: default avatarHuangjie <huangjie1663@phytium.com.cn>
Closes: https://lore.kernel.org/arm-scmi/20250123083323.2363749-1-jackhuang021@gmail.com/


Signed-off-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Cc: stable@vger.kernel.org # 5.18.x
Message-Id: <20250310175800.1444293-1-cristian.marussi@arm.com>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent 9ca67840

drivers/firmware/arm_scmi/driver.c

+8 −5
Original line number Diff line number Diff line
@@ -1248,7 +1248,8 @@ static void xfer_put(const struct scmi_protocol_handle *ph, 
}



static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo,

				      struct scmi_xfer *xfer, ktime_t stop)

				      struct scmi_xfer *xfer, ktime_t stop,

				      bool *ooo)

{

	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
@@ -1257,7 +1258,7 @@ static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo, 
	 * in case of out-of-order receptions of delayed responses

	 */

	return info->desc->ops->poll_done(cinfo, xfer) ||

	       try_wait_for_completion(&xfer->done) ||

	       (*ooo = try_wait_for_completion(&xfer->done)) ||

	       ktime_after(ktime_get(), stop);

}
@@ -1274,15 +1275,17 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc, 
		 * itself to support synchronous commands replies.

		 */

		if (!desc->sync_cmds_completed_on_ret) {

			bool ooo = false;



			/*

			 * Poll on xfer using transport provided .poll_done();

			 * assumes no completion interrupt was available.

			 */

			ktime_t stop = ktime_add_ms(ktime_get(), timeout_ms);



			spin_until_cond(scmi_xfer_done_no_timeout(cinfo,

								  xfer, stop));

			if (ktime_after(ktime_get(), stop)) {

			spin_until_cond(scmi_xfer_done_no_timeout(cinfo, xfer,

								  stop, &ooo));

			if (!ooo && !info->desc->ops->poll_done(cinfo, xfer)) {

				dev_err(dev,

					"timed out in resp(caller: %pS) - polling\n",

					(void *)_RET_IP_);