Date: Mon, 3 Jan 2022 19:34:29 -0700 From: Alan Somers <asomers@freebsd.org> To: Robert Wing <rew@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org Subject: Re: git: bb8441184bab - main - cam: don't lock while handling an AC_UNIT_ATTENTION Message-ID: <CAOtMX2hA6MkSnEhmHpz1B-FP-8FJcJZBjjcu5TYGj%2ByeceWfbA@mail.gmail.com> In-Reply-To: <202201040201.20421vmw040882@gitrepo.freebsd.org> References: <202201040201.20421vmw040882@gitrepo.freebsd.org>
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On Mon, Jan 3, 2022 at 7:02 PM Robert Wing <rew@freebsd.org> wrote: > > The branch main has been updated by rew: > > URL: https://cgit.FreeBSD.org/src/commit/?id=bb8441184bab60cd8a07c2b94bd6c4ae8b56ec25 > > commit bb8441184bab60cd8a07c2b94bd6c4ae8b56ec25 > Author: Robert Wing <rew@FreeBSD.org> > AuthorDate: 2022-01-04 01:21:58 +0000 > Commit: Robert Wing <rew@FreeBSD.org> > CommitDate: 2022-01-04 01:56:48 +0000 > > cam: don't lock while handling an AC_UNIT_ATTENTION > > Don't take the device_mtx lock in daasync() when handling an > AC_UNIT_ATTENTION. Instead, assert the lock is held before modifying the > periph's softc flags. > > The device_mtx lock is taken in xptdevicetraverse() before daasync() > is eventually called in xpt_async_bcast(). > > PR: 240917, 226510, 226578 > Reviewed by: imp > MFC after: 3 weeks > Differential Revision: https://reviews.freebsd.org/D27735 > --- > sys/cam/scsi/scsi_da.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/sys/cam/scsi/scsi_da.c b/sys/cam/scsi/scsi_da.c > index 243e86d18caa..df8791e4b23e 100644 > --- a/sys/cam/scsi/scsi_da.c > +++ b/sys/cam/scsi/scsi_da.c > @@ -2158,7 +2158,7 @@ daasync(void *callback_arg, u_int32_t code, > } > break; > } > - case AC_UNIT_ATTENTION: > + case AC_UNIT_ATTENTION: /* Called for this path: periph locked */ > { > union ccb *ccb; > int error_code, sense_key, asc, ascq; > @@ -2168,9 +2168,7 @@ daasync(void *callback_arg, u_int32_t code, > > /* > * 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. > + * handled by daerror(). > */ > if (xpt_path_periph(ccb->ccb_h.path) != periph && > scsi_extract_sense_ccb(ccb, > @@ -2178,22 +2176,19 @@ daasync(void *callback_arg, u_int32_t code, > if (asc == 0x2A && ascq == 0x09) { > xpt_print(ccb->ccb_h.path, > "Capacity data has changed\n"); > - cam_periph_lock(periph); > + cam_periph_assert(periph, MA_OWNED); > softc->flags &= ~DA_FLAG_PROBED; > dareprobe(periph); > - cam_periph_unlock(periph); > } else if (asc == 0x28 && ascq == 0x00) { > - cam_periph_lock(periph); > + cam_periph_assert(periph, MA_OWNED); > softc->flags &= ~DA_FLAG_PROBED; > - cam_periph_unlock(periph); > disk_media_changed(softc->disk, M_NOWAIT); > } else if (asc == 0x3F && ascq == 0x03) { > xpt_print(ccb->ccb_h.path, > "INQUIRY data has changed\n"); > - cam_periph_lock(periph); > + cam_periph_assert(periph, MA_OWNED); > softc->flags &= ~DA_FLAG_PROBED; > dareprobe(periph); > - cam_periph_unlock(periph); > } > } > break; Thanks a lot!
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