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Only assert locked for many async events.

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Many async events that we see are called for this specific path. When
calling an async callback for a targetted device, XTP will lock that
specific device's path lock (same as what cam_periph_lock does). For
those AC_ events, assert we have the lock rather than trying to
recusrively take it (which causes panics since it's not recursive).

Add annotations about this and about the fact that AC_SCSI_AEN events
are generated now only in the ata stack (which cannot have a scsi_da
attachment). Leave it in place in case I've overlooked something as
the code is harmless.

This is fallout from my attempts to "fix" locking for softc->flags in
r330796 that's not been triggered often enough to get my attention
until now.

Sponsored by: Netflix
MFC After: 3 days
Differential Revision: https://reviews.freebsd.org/D17837
This commit is contained in:
Warner Losh 2018-11-05 18:47:29 +00:00
parent bdf12807be
commit 74c0112fef
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=340155
1 changed files with 17 additions and 14 deletions
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31
sys/cam/scsi/scsi_da.c
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@ -2005,7 +2005,7 @@ daasync(void *callback_arg, u_int32_t code,
periph = (struct cam_periph *)callback_arg;
switch (code) {
case AC_FOUND_DEVICE:
case AC_FOUND_DEVICE: /* callback to create periph, no locking yet */
{
struct ccb_getdev *cgd;
cam_status status;
@ -2041,7 +2041,7 @@ daasync(void *callback_arg, u_int32_t code,
"due to status 0x%x\n", status);
return;
}
case AC_ADVINFO_CHANGED:
case AC_ADVINFO_CHANGED: /* Doesn't touch periph */
{
uintptr_t buftype;
@ -2064,8 +2064,10 @@ daasync(void *callback_arg, u_int32_t code,
ccb = (union ccb *)arg;
/*
* Handle all UNIT ATTENTIONs except our own,
* as they will be handled by daerror().
* Handle all UNIT ATTENTIONs except our own, as they will be
* handled by daerror(). Since this comes from a different periph,
* that periph's lock is held, not ours, so we have to take it ours
* out to touch softc flags.
*/
if (xpt_path_periph(ccb->ccb_h.path) != periph &&
scsi_extract_sense_ccb(ccb,
@ -2093,9 +2095,13 @@ daasync(void *callback_arg, u_int32_t code,
}
break;
}
case AC_SCSI_AEN:
case AC_SCSI_AEN: /* Called for this path: periph locked */
/*
* Appears to be currently unused for SCSI devices, only ata SIMs
* generate this.
*/
cam_periph_assert(periph, MA_OWNED);
softc = (struct da_softc *)periph->softc;
cam_periph_lock(periph);
if (!cam_iosched_has_work_flags(softc->cam_iosched, DA_WORK_TUR) &&
(softc->flags & DA_FLAG_TUR_PENDING) == 0) {
if (da_periph_acquire(periph, DA_REF_TUR) == 0) {
@ -2103,31 +2109,28 @@ daasync(void *callback_arg, u_int32_t code,
daschedule(periph);
}
}
cam_periph_unlock(periph);
/* FALLTHROUGH */
case AC_SENT_BDR:
case AC_BUS_RESET:
case AC_SENT_BDR: /* Called for this path: periph locked */
case AC_BUS_RESET: /* Called for this path: periph locked */
{
struct ccb_hdr *ccbh;
cam_periph_assert(periph, MA_OWNED);
softc = (struct da_softc *)periph->softc;
/*
* Don't fail on the expected unit attention
* that will occur.
*/
cam_periph_lock(periph);
softc->flags |= DA_FLAG_RETRY_UA;
LIST_FOREACH(ccbh, &softc->pending_ccbs, periph_links.le)
ccbh->ccb_state |= DA_CCB_RETRY_UA;
cam_periph_unlock(periph);
break;
}
case AC_INQ_CHANGED:
cam_periph_lock(periph);
case AC_INQ_CHANGED: /* Called for this path: periph locked */
cam_periph_assert(periph, MA_OWNED);
softc = (struct da_softc *)periph->softc;
softc->flags &= ~DA_FLAG_PROBED;
dareprobe(periph);
cam_periph_unlock(periph);
break;
default:
break;