857bb3d01e
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
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