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firmware: arm_scmi: Fix timeout checks on polling path

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[ Upstream commit c23c03bf1faa1e76be1eba35bad6da6a2a7c95ee ]

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: 31d2f803c1 ("firmware: arm_scmi: Add sync_cmds_completed_on_ret transport flag")
Reported-by: Huangjie <huangjie1663@phytium.com.cn>
Closes: https://lore.kernel.org/arm-scmi/20250123083323.2363749-1-jackhuang021@gmail.com/
Signed-off-by: Cristian 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: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Cristian Marussi
2025-03-10 17:58:00 +00:00
committed by Greg Kroah-Hartman
parent b388129425
commit 2402a3ef9e
1 changed files with 8 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/firmware/arm_scmi/driver.c
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@@ -1075,7 +1075,8 @@ 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);
@@ -1084,7 +1085,7 @@ 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);
}
@@ -1101,15 +1102,17 @@ 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_);