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* [PATCH] scsi/mesh: Fix panic after host or bus reset
@ 2020-07-22 23:25 Finn Thain
  2020-07-25  2:50 ` Martin K. Petersen
  0 siblings, 1 reply; 2+ messages in thread
From: Finn Thain @ 2020-07-22 23:25 UTC (permalink / raw)
  To: James E.J. Bottomley, Martin K. Petersen
  Cc: Paul Mackerras, linux-scsi, linux-kernel

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'.

Cc: Paul Mackerras <paulus@ozlabs.org>
Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Reported-and-tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 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 */
-- 
2.26.2


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] scsi/mesh: Fix panic after host or bus reset
  2020-07-22 23:25 [PATCH] scsi/mesh: Fix panic after host or bus reset Finn Thain
@ 2020-07-25  2:50 ` Martin K. Petersen
  0 siblings, 0 replies; 2+ messages in thread
From: Martin K. Petersen @ 2020-07-25  2:50 UTC (permalink / raw)
  To: James E.J. Bottomley, Finn Thain
  Cc: Martin K . Petersen, Paul Mackerras, linux-kernel, linux-scsi

On Thu, 23 Jul 2020 09:25:51 +1000, Finn Thain wrote:

> 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..
> 
> [...]

Applied to 5.9/scsi-queue, thanks!

[1/1] scsi: mesh: Fix panic after host or bus reset
      https://git.kernel.org/mkp/scsi/c/edd7dd2292ab

-- 
Martin K. Petersen	Oracle Linux Engineering

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2020-07-22 23:25 [PATCH] scsi/mesh: Fix panic after host or bus reset Finn Thain
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