From: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> [ Upstream commit edd7dd2292ab9c3628b65c4d04514c3068ad54f6 ] Booting Linux with a Conner CP3200 drive attached to the MESH SCSI bus results in EH measures and a panic: [ 25.499838] mesh: configured for synchronous 5 MB/s [ 25.787154] mesh: performing initial bus reset... [ 29.867115] scsi host0: MESH [ 29.929527] mesh: target 0 synchronous at 3.6 MB/s [ 29.998763] scsi 0:0:0:0: Direct-Access CONNER CP3200-200mb-3.5 4040 PQ: 0 ANSI: 1 CCS [ 31.989975] sd 0:0:0:0: [sda] 415872 512-byte logical blocks: (213 MB/203 MiB) [ 32.070975] sd 0:0:0:0: [sda] Write Protect is off [ 32.137197] sd 0:0:0:0: [sda] Mode Sense: 5b 00 00 08 [ 32.209661] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 32.332708] sda: [mac] sda1 sda2 sda3 [ 32.417733] sd 0:0:0:0: [sda] Attached SCSI disk ... snip ... [ 76.687067] mesh_abort((ptrval)) [ 76.743606] mesh: state at (ptrval), regs at (ptrval), dma at (ptrval) [ 76.810798] ct=6000 seq=86 bs=4017 fc= 0 exc= 0 err= 0 im= 7 int= 0 sp=85 [ 76.880720] dma stat=84e0 cmdptr=1f73d000 [ 76.941387] phase=4 msgphase=0 conn_tgt=0 data_ptr=24576 [ 77.005567] dma_st=1 dma_ct=0 n_msgout=0 [ 77.065456] target 0: req=(ptrval) goes_out=0 saved_ptr=0 [ 77.130512] mesh_abort((ptrval)) [ 77.187670] mesh: state at (ptrval), regs at (ptrval), dma at (ptrval) [ 77.255594] ct=6000 seq=86 bs=4017 fc= 0 exc= 0 err= 0 im= 7 int= 0 sp=85 [ 77.325778] dma stat=84e0 cmdptr=1f73d000 [ 77.387239] phase=4 msgphase=0 conn_tgt=0 data_ptr=24576 [ 77.453665] dma_st=1 dma_ct=0 n_msgout=0 [ 77.515900] target 0: req=(ptrval) goes_out=0 saved_ptr=0 [ 77.582902] mesh_host_reset [ 88.187083] Kernel panic - not syncing: mesh: double DMA start ! [ 88.254510] CPU: 0 PID: 358 Comm: scsi_eh_0 Not tainted 5.6.13-pmac #1 [ 88.323302] Call Trace: [ 88.378854] [e16ddc58] [c0027080] panic+0x13c/0x308 (unreliable) [ 88.446221] [e16ddcb8] [c02b2478] mesh_start.part.12+0x130/0x414 [ 88.513298] [e16ddcf8] [c02b2fc8] mesh_queue+0x54/0x70 [ 88.577097] [e16ddd18] [c02a1848] scsi_send_eh_cmnd+0x374/0x384 [ 88.643476] [e16dddc8] [c02a1938] scsi_eh_tur+0x5c/0xb8 [ 88.707878] [e16dddf8] [c02a1ab8] scsi_eh_test_devices+0x124/0x178 [ 88.775663] [e16dde28] [c02a2094] scsi_eh_ready_devs+0x588/0x8a8 [ 88.843124] [e16dde98] [c02a31d8] scsi_error_handler+0x344/0x520 [ 88.910697] [e16ddf08] [c00409c8] kthread+0xe4/0xe8 [ 88.975166] [e16ddf38] [c000f234] ret_from_kernel_thread+0x14/0x1c [ 89.044112] Rebooting in 180 seconds.. In theory, a panic can happen after a bus or host reset with dma_started flag set. Fix this by halting the DMA before reinitializing the host. Don't assume that ms->current_req is set when halt_dma() is invoked as it may not hold for bus or host reset. BTW, this particular Conner drive can be made to work by inhibiting disconnect/reselect with 'mesh.resel_targets=0'. Link: https://lore.kernel.org/r/3952bc691e150a7128b29120999b6092071b039a.1595460351.git.fthain@xxxxxxxxxxxxxxxxxxx Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: Paul Mackerras <paulus@xxxxxxxxxx> Reported-and-tested-by: Stan Johnson <userm57@xxxxxxxxx> Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/scsi/mesh.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/mesh.c b/drivers/scsi/mesh.c index 74fb50644678d..4dd50db906779 100644 --- a/drivers/scsi/mesh.c +++ b/drivers/scsi/mesh.c @@ -1045,6 +1045,8 @@ static void handle_error(struct mesh_state *ms) while ((in_8(&mr->bus_status1) & BS1_RST) != 0) udelay(1); printk("done\n"); + if (ms->dma_started) + halt_dma(ms); handle_reset(ms); /* request_q is empty, no point in mesh_start() */ return; @@ -1357,7 +1359,8 @@ static void halt_dma(struct mesh_state *ms) ms->conn_tgt, ms->data_ptr, scsi_bufflen(cmd), ms->tgts[ms->conn_tgt].data_goes_out); } - scsi_dma_unmap(cmd); + if (cmd) + scsi_dma_unmap(cmd); ms->dma_started = 0; } @@ -1712,6 +1715,9 @@ static int mesh_host_reset(struct scsi_cmnd *cmd) spin_lock_irqsave(ms->host->host_lock, flags); + if (ms->dma_started) + halt_dma(ms); + /* Reset the controller & dbdma channel */ out_le32(&md->control, (RUN|PAUSE|FLUSH|WAKE) << 16); /* stop dma */ out_8(&mr->exception, 0xff); /* clear all exception bits */ -- 2.25.1
