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Fix spurious timeouts on commands sent to mps(4) and mpr(4) controllers.

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mps_wait_command() and mpr_wait_command() were using getmicrotime() to
determine elapsed time when checking for a timeout in polled mode.
getmicrotime() isn't guaranteed to monotonically increase, and that
caused spurious timeouts occasionally.

Switch to using getmicrouptime(), which does increase monotonically.
This fixes the spurious timeouts in my test case.

Reviewed by:	slm, scottl
MFC after:	3 days
Sponsored by:	Spectra Logic
This commit is contained in:
ken 2017-07-19 15:39:01 +00:00
parent 9d0182f904
commit d889c07bf6
2 changed files with 30 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
sys/dev/mpr/mpr.c
View File

@ -3286,9 +3286,17 @@ mpr_wait_command(struct mpr_softc *sc, struct mpr_command *cm, int timeout,
if (curthread->td_pflags & TDP_NOSLEEPING)
#endif //__FreeBSD_version >= 1000029
sleep_flag = NO_SLEEP;
getmicrotime(&start_time);
getmicrouptime(&start_time);
if (mtx_owned(&sc->mpr_mtx) && sleep_flag == CAN_SLEEP) {
error = msleep(cm, &sc->mpr_mtx, 0, "mprwait", timeout*hz);
if (error == EWOULDBLOCK) {
/*
* Record the actual elapsed time in the case of a
* timeout for the message below.
*/
getmicrouptime(&cur_time);
timevalsub(&cur_time, &start_time);
}
} else {
while ((cm->cm_flags & MPR_CM_FLAGS_COMPLETE) == 0) {
mpr_intr_locked(sc);
@ -3297,8 +3305,9 @@ mpr_wait_command(struct mpr_softc *sc, struct mpr_command *cm, int timeout,
else
DELAY(50000);
getmicrotime(&cur_time);
if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
getmicrouptime(&cur_time);
timevalsub(&cur_time, &start_time);
if (cur_time.tv_sec > timeout) {
error = EWOULDBLOCK;
break;
}
@ -3306,7 +3315,9 @@ mpr_wait_command(struct mpr_softc *sc, struct mpr_command *cm, int timeout,
}
if (error == EWOULDBLOCK) {
mpr_dprint(sc, MPR_FAULT, "Calling Reinit from %s\n", __func__);
mpr_dprint(sc, MPR_FAULT, "Calling Reinit from %s, timeout=%d,"
" elapsed=%jd\n", __func__, timeout,
(intmax_t)cur_time.tv_sec);
rc = mpr_reinit(sc);
mpr_dprint(sc, MPR_FAULT, "Reinit %s\n", (rc == 0) ? "success" :
"failed");

19
sys/dev/mps/mps.c
View File

@ -2551,10 +2551,18 @@ mps_wait_command(struct mps_softc *sc, struct mps_command *cm, int timeout,
*/
if (curthread->td_no_sleeping != 0)
sleep_flag = NO_SLEEP;
getmicrotime(&start_time);
getmicrouptime(&start_time);
if (mtx_owned(&sc->mps_mtx) && sleep_flag == CAN_SLEEP) {
cm->cm_flags |= MPS_CM_FLAGS_WAKEUP;
error = msleep(cm, &sc->mps_mtx, 0, "mpswait", timeout*hz);
if (error == EWOULDBLOCK) {
/*
* Record the actual elapsed time in the case of a
* timeout for the message below.
*/
getmicrouptime(&cur_time);
timevalsub(&cur_time, &start_time);
}
} else {
while ((cm->cm_flags & MPS_CM_FLAGS_COMPLETE) == 0) {
mps_intr_locked(sc);
@ -2563,8 +2571,9 @@ mps_wait_command(struct mps_softc *sc, struct mps_command *cm, int timeout,
else
DELAY(50000);
getmicrotime(&cur_time);
if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
getmicrouptime(&cur_time);
timevalsub(&cur_time, &start_time);
if (cur_time.tv_sec > timeout) {
error = EWOULDBLOCK;
break;
}
@ -2572,7 +2581,9 @@ mps_wait_command(struct mps_softc *sc, struct mps_command *cm, int timeout,
}
if (error == EWOULDBLOCK) {
mps_dprint(sc, MPS_FAULT, "Calling Reinit from %s\n", __func__);
mps_dprint(sc, MPS_FAULT, "Calling Reinit from %s, timeout=%d,"
" elapsed=%jd\n", __func__, timeout,
(intmax_t)cur_time.tv_sec);
rc = mps_reinit(sc);
mps_dprint(sc, MPS_FAULT, "Reinit %s\n", (rc == 0) ? "success" :
"failed");