firewire/sbp: try to improve locking, plus a few style nits
This change tries to fix the most obvious locking problems. sbp_cam_scan_lun() is never called with the sbp lock held, so the lock needs to be acquired internally (if it's needed at all). Without this change a kernel with INVARIANTS panics when a firewire disk is connected: panic: mutex sbp not owned at /usr/src/sys/dev/firewire/sbp.c:967 KDB: stack backtrace: db_trace_self_wrapper() at 0xffffffff80420bbb = db_trace_self_wrapper+0x2b/frame 0xfffffe0504df0930 kdb_backtrace() at 0xffffffff80670359 = kdb_backtrace+0x39/frame 0xfffffe0504df09e0 vpanic() at 0xffffffff8063986c = vpanic+0x14c/frame 0xfffffe0504df0a20 panic() at 0xffffffff806395b3 = panic+0x43/frame 0xfffffe0504df0a80 __mtx_assert() at 0xffffffff8061c40d = __mtx_assert+0xed/frame 0xfffffe0504df0ac0 sbp_cam_scan_lun() at 0xffffffff80474667 = sbp_cam_scan_lun+0x37/frame 0xfffffe0504df0af0 xpt_done_process() at 0xffffffff802aacfa = xpt_done_process+0x2da/frame 0xfffffe0504df0b30 xpt_done_td() at 0xffffffff802ac2e5 = xpt_done_td+0xd5/frame 0xfffffe0504df0b80 fork_exit() at 0xffffffff805ff72f = fork_exit+0xdf/frame 0xfffffe0504df0bf0 fork_trampoline() at 0xffffffff8082483e = fork_trampoline+0xe/frame 0xfffffe0504df0bf0 --- trap 0, rip = 0, rsp = 0, rbp = 0 --- Also, I tried to reduce the scope of the sbp lock to avoid holding it while doing bus_dma allocations. The code badly needs some re-engineering. SBP really should implement a CAM transport, so that it avoids control flow inversion when re-scanning the bus. Also, the sbp lock seems to be too coarse. Additionally, the commit includes some changes not related to locking. - sbp_cam_scan_lun: restore CAM_DEV_QFREEZE before re-queueing the ccb because xpt_setup_ccb resets ccb_h.flags - sbp_post_busreset: call xpt_release_simq only if it's actually frozen - don't place private SIMQ_FREEZED flag (sic, "freezed") into sim->flags, use sbp->flags for that - some style fixes and control flow enhancements Reviewed by: sbruno MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D9898
This commit is contained in:
Andriy Gapon
parent
3798444e9c
commit
857bb3d01e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=314864
@ -425,7 +425,6 @@ sbp_alloc_lun(struct sbp_target *target)
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int maxlun, lun, i;
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sbp = target->sbp;
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SBP_LOCK_ASSERT(sbp);
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crom_init_context(&cc, target->fwdev->csrrom);
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/* XXX shoud parse appropriate unit directories only */
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maxlun = -1;
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@ -558,7 +557,9 @@ END_DEBUG
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goto next;
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}
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callout_init_mtx(&ocb->timer, &sbp->mtx, 0);
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SBP_LOCK(sbp);
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sbp_free_ocb(sdev, ocb);
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SBP_UNLOCK(sbp);
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}
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next:
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crom_next(&cc);
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@ -687,9 +688,8 @@ END_DEBUG
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&& crom_has_specver((fwdev)->csrrom, CSRVAL_ANSIT10, CSRVAL_T10SBP2))
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static void
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sbp_probe_target(void *arg)
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sbp_probe_target(struct sbp_target *target)
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{
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struct sbp_target *target = (struct sbp_target *)arg;
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struct sbp_softc *sbp = target->sbp;
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struct sbp_dev *sdev;
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int i, alive;
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@ -701,8 +701,6 @@ SBP_DEBUG(1)
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(!alive) ? " not " : "");
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END_DEBUG
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sbp = target->sbp;
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SBP_LOCK_ASSERT(sbp);
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sbp_alloc_lun(target);
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/* XXX untimeout mgm_ocb and dequeue */
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@ -718,7 +716,9 @@ END_DEBUG
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sbp_probe_lun(sdev);
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sbp_show_sdev_info(sdev);
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SBP_LOCK(sbp);
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sbp_abort_all_ocbs(sdev, CAM_SCSI_BUS_RESET);
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SBP_UNLOCK(sbp);
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switch (sdev->status) {
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case SBP_DEV_RESET:
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/* new or revived target */
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@ -773,9 +773,9 @@ SBP_DEBUG(0)
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printf("sbp_post_busreset\n");
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END_DEBUG
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SBP_LOCK(sbp);
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if ((sbp->sim->flags & SIMQ_FREEZED) == 0) {
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if ((sbp->flags & SIMQ_FREEZED) == 0) {
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xpt_freeze_simq(sbp->sim, /*count*/1);
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sbp->sim->flags |= SIMQ_FREEZED;
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sbp->flags |= SIMQ_FREEZED;
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}
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microtime(&sbp->last_busreset);
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SBP_UNLOCK(sbp);
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@ -800,19 +800,15 @@ END_DEBUG
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sbp_cold--;
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SBP_LOCK(sbp);
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#if 0
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/*
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* XXX don't let CAM the bus rest.
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* CAM tries to do something with freezed (DEV_RETRY) devices.
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*/
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xpt_async(AC_BUS_RESET, sbp->path, /*arg*/ NULL);
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#endif
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/* Garbage Collection */
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for (i = 0; i < SBP_NUM_TARGETS; i++) {
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target = &sbp->targets[i];
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if (target->fwdev == NULL)
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continue;
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STAILQ_FOREACH(fwdev, &sbp->fd.fc->devices, link)
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if (target->fwdev == NULL || target->fwdev == fwdev)
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if (target->fwdev == fwdev)
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break;
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if (fwdev == NULL) {
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/* device has removed in lower driver */
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@ -820,6 +816,7 @@ END_DEBUG
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sbp_free_target(target);
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}
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}
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/* traverse device list */
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STAILQ_FOREACH(fwdev, &sbp->fd.fc->devices, link) {
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SBP_DEBUG(0)
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@ -846,12 +843,24 @@ END_DEBUG
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continue;
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}
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}
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sbp_probe_target((void *)target);
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/*
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* It is safe to drop the lock here as the target is already
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* reserved, so there should be no contenders for it.
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* And the target is not yet exposed, so there should not be
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* any other accesses to it.
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* Finally, the list being iterated is protected somewhere else.
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*/
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SBP_UNLOCK(sbp);
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sbp_probe_target(target);
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SBP_LOCK(sbp);
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if (target->num_lun == 0)
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sbp_free_target(target);
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}
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xpt_release_simq(sbp->sim, /*run queue*/TRUE);
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sbp->sim->flags &= ~SIMQ_FREEZED;
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if ((sbp->flags & SIMQ_FREEZED) != 0) {
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xpt_release_simq(sbp->sim, /*run queue*/TRUE);
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sbp->flags &= ~SIMQ_FREEZED;
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}
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SBP_UNLOCK(sbp);
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}
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@ -959,30 +968,36 @@ sbp_next_dev(struct sbp_target *target, int lun)
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static void
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sbp_cam_scan_lun(struct cam_periph *periph, union ccb *ccb)
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{
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struct sbp_softc *sbp;
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struct sbp_target *target;
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struct sbp_dev *sdev;
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sdev = (struct sbp_dev *) ccb->ccb_h.ccb_sdev_ptr;
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target = sdev->target;
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SBP_LOCK_ASSERT(target->sbp);
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sbp = target->sbp;
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SBP_LOCK(sbp);
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SBP_DEBUG(0)
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device_printf(sdev->target->sbp->fd.dev,
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device_printf(sbp->fd.dev,
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"%s:%s\n", __func__, sdev->bustgtlun);
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END_DEBUG
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if ((ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP) {
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sdev->status = SBP_DEV_ATTACHED;
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} else {
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device_printf(sdev->target->sbp->fd.dev,
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device_printf(sbp->fd.dev,
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"%s:%s failed\n", __func__, sdev->bustgtlun);
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}
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sdev = sbp_next_dev(target, sdev->lun_id + 1);
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if (sdev == NULL) {
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SBP_UNLOCK(sbp);
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free(ccb, M_SBP);
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return;
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}
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/* reuse ccb */
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xpt_setup_ccb(&ccb->ccb_h, sdev->path, SCAN_PRI);
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ccb->ccb_h.ccb_sdev_ptr = sdev;
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ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
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SBP_UNLOCK(sbp);
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xpt_action(ccb);
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xpt_release_devq(sdev->path, sdev->freeze, TRUE);
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sdev->freeze = 1;
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@ -1011,6 +1026,8 @@ END_DEBUG
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printf("sbp_cam_scan_target: malloc failed\n");
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return;
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}
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SBP_UNLOCK(target->sbp);
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xpt_setup_ccb(&ccb->ccb_h, sdev->path, SCAN_PRI);
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ccb->ccb_h.func_code = XPT_SCAN_LUN;
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ccb->ccb_h.cbfcnp = sbp_cam_scan_lun;
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@ -1020,6 +1037,8 @@ END_DEBUG
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/* The scan is in progress now. */
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xpt_action(ccb);
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SBP_LOCK(target->sbp);
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xpt_release_devq(sdev->path, sdev->freeze, TRUE);
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sdev->freeze = 1;
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}
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@ -1977,8 +1996,8 @@ END_DEBUG
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sbp->fd.post_explore = sbp_post_explore;
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if (fc->status != -1) {
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sbp_post_busreset((void *)sbp);
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sbp_post_explore((void *)sbp);
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sbp_post_busreset(sbp);
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sbp_post_explore(sbp);
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}
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SBP_LOCK(sbp);
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xpt_async(AC_BUS_RESET, sbp->path, /*arg*/ NULL);
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