Date: Mon, 11 Nov 2019 17:36:52 +0000 (UTC) From: Warner Losh <imp@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r354622 - head/sys/cam/scsi Message-ID: <201911111736.xABHaq30099045@repo.freebsd.org>
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Author: imp Date: Mon Nov 11 17:36:52 2019 New Revision: 354622 URL: https://svnweb.freebsd.org/changeset/base/354622 Log: Update the softc state of the da driver before releasing the CCB. There are contexts where releasing the ccb triggers dastart() to be run inline. When da was written, there was always a deferral, so it didn't matter much. Now, with direct dispatch, we can call dastart from the dadone* routines. If the probe state isn't updated, then dastart will redo things with stale information. This normally isn't a problem, because we run the probe state machine once at boot... Except that we also run it for each open of the device, which means we can have multiple threads racing each other to try to kick off the probe. However, if we update the state before we release the CCB, we can avoid the race. While it's needed only for the probewp and proberc* states, do it everywhere because it won't hurt the other places. The race here happens because we reprobe dozens of times on boot when drives have lots of partitions. We should consider caching this info for 1-2 seconds to avoid this thundering hurd. Reviewed by: scottl, ken Differential Revision: https://reviews.freebsd.org/D22295 Modified: head/sys/cam/scsi/scsi_da.c Modified: head/sys/cam/scsi/scsi_da.c ============================================================================== --- head/sys/cam/scsi/scsi_da.c Mon Nov 11 17:36:47 2019 (r354621) +++ head/sys/cam/scsi/scsi_da.c Mon Nov 11 17:36:52 2019 (r354622) @@ -4645,11 +4645,11 @@ dadone_probewp(struct cam_periph *periph, union ccb *d } free(csio->data_ptr, M_SCSIDA); - xpt_release_ccb(done_ccb); if ((softc->flags & DA_FLAG_CAN_RC16) != 0) softc->state = DA_STATE_PROBE_RC16; else softc->state = DA_STATE_PROBE_RC; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -4709,8 +4709,8 @@ dadone_proberc(struct cam_periph *periph, union ccb *d */ if (maxsector == 0xffffffff) { free(rdcap, M_SCSIDA); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_RC16; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -4816,8 +4816,8 @@ dadone_proberc(struct cam_periph *periph, union ccb *d cam_periph_assert(periph, MA_OWNED); softc->flags &= ~DA_FLAG_CAN_RC16; free(rdcap, M_SCSIDA); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_RC; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -4924,14 +4924,14 @@ dadone_proberc(struct cam_periph *periph, union ccb *d dadeleteflag(softc, DA_DELETE_WS10, 1); dadeleteflag(softc, DA_DELETE_UNMAP, 1); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_LBP; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_BDC; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -4988,8 +4988,8 @@ dadone_probelbp(struct cam_periph *periph, union ccb * } free(lbp, M_SCSIDA); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_BLK_LIMITS; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -5082,8 +5082,8 @@ dadone_probeblklimits(struct cam_periph *periph, union } free(block_limits, M_SCSIDA); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_BDC; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -5183,8 +5183,8 @@ dadone_probebdc(struct cam_periph *periph, union ccb * } free(bdc, M_SCSIDA); - xpt_release_ccb(done_ccb); softc->state = DA_STATE_PROBE_ATA; + xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); return; } @@ -5323,8 +5323,8 @@ dadone_probeata(struct cam_periph *periph, union ccb * continue_probe = 1; } if (continue_probe != 0) { - xpt_release_ccb(done_ccb); xpt_schedule(periph, priority); + xpt_release_ccb(done_ccb); return; } else daprobedone(periph, done_ccb); @@ -5813,8 +5813,8 @@ dadone_tur(struct cam_periph *periph, union ccb *done_ /*timeout*/0, /*getcount_only*/0); } - xpt_release_ccb(done_ccb); softc->flags &= ~DA_FLAG_TUR_PENDING; + xpt_release_ccb(done_ccb); da_periph_release_locked(periph, DA_REF_TUR); return; }
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