6.6-stable review patch. If anyone has any objections, please let me know.
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From: Cristian Marussi cristian.marussi@arm.com
[ 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: 31d2f803c19c ("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... 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 --- drivers/firmware/arm_scmi/driver.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 09aaad6dce043..65d1e66a347d7 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -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_);