| Message ID | 1526065486-38860-1-git-send-email-ukrishn@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, May 11, 2018 at 02:04:46PM -0500, Uma Krishnan wrote: > The following Oops may be encountered if the device is reset, i.e. EEH > recovery, while there is heavy I/O traffic: > > 59:mon> t > [c000200db64bb680] c008000009264c40 cxlflash_queuecommand+0x3b8/0x500 > [cxlflash] > [c000200db64bb770] c00000000090d3b0 scsi_dispatch_cmd+0x130/0x2f0 > [c000200db64bb7f0] c00000000090fdd8 scsi_request_fn+0x3c8/0x8d0 > [c000200db64bb900] c00000000067f528 __blk_run_queue+0x68/0xb0 > [c000200db64bb930] c00000000067ab80 __elv_add_request+0x140/0x3c0 > [c000200db64bb9b0] c00000000068daac blk_execute_rq_nowait+0xec/0x1a0 > [c000200db64bba00] c00000000068dbb0 blk_execute_rq+0x50/0xe0 > [c000200db64bba50] c0000000006b2040 sg_io+0x1f0/0x520 > [c000200db64bbaf0] c0000000006b2e94 scsi_cmd_ioctl+0x534/0x610 > [c000200db64bbc20] c000000000926208 sd_ioctl+0x118/0x280 > [c000200db64bbcc0] c00000000069f7ac blkdev_ioctl+0x7fc/0xe30 > [c000200db64bbd20] c000000000439204 block_ioctl+0x84/0xa0 > [c000200db64bbd40] c0000000003f8514 do_vfs_ioctl+0xd4/0xa00 > [c000200db64bbde0] c0000000003f8f04 SyS_ioctl+0xc4/0x130 > [c000200db64bbe30] c00000000000b184 system_call+0x58/0x6c > > When there is no room to send the I/O request, the cached room is refreshed > by reading the memory mapped command room value from the AFU. The AFU > register mapping is refreshed during a reset, creating a race condition > that can lead to the Oops above. > > During a device reset, the AFU should not be unmapped until all the active > send threads quiesce. An atomic counter, cmds_active, is currently used to > track internal AFU commands and quiesce during reset. This same counter can > also be used for the active send threads. > > Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com> Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c index a24d7e6..dad2be6 100644 --- a/drivers/scsi/cxlflash/main.c +++ b/drivers/scsi/cxlflash/main.c @@ -616,6 +616,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) rc = 0; goto out; default: + atomic_inc(&afu->cmds_active); break; } @@ -641,6 +642,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) memcpy(cmd->rcb.cdb, scp->cmnd, sizeof(cmd->rcb.cdb)); rc = afu->send_cmd(afu, cmd); + atomic_dec(&afu->cmds_active); out: return rc; }
The following Oops may be encountered if the device is reset, i.e. EEH recovery, while there is heavy I/O traffic: 59:mon> t [c000200db64bb680] c008000009264c40 cxlflash_queuecommand+0x3b8/0x500 [cxlflash] [c000200db64bb770] c00000000090d3b0 scsi_dispatch_cmd+0x130/0x2f0 [c000200db64bb7f0] c00000000090fdd8 scsi_request_fn+0x3c8/0x8d0 [c000200db64bb900] c00000000067f528 __blk_run_queue+0x68/0xb0 [c000200db64bb930] c00000000067ab80 __elv_add_request+0x140/0x3c0 [c000200db64bb9b0] c00000000068daac blk_execute_rq_nowait+0xec/0x1a0 [c000200db64bba00] c00000000068dbb0 blk_execute_rq+0x50/0xe0 [c000200db64bba50] c0000000006b2040 sg_io+0x1f0/0x520 [c000200db64bbaf0] c0000000006b2e94 scsi_cmd_ioctl+0x534/0x610 [c000200db64bbc20] c000000000926208 sd_ioctl+0x118/0x280 [c000200db64bbcc0] c00000000069f7ac blkdev_ioctl+0x7fc/0xe30 [c000200db64bbd20] c000000000439204 block_ioctl+0x84/0xa0 [c000200db64bbd40] c0000000003f8514 do_vfs_ioctl+0xd4/0xa00 [c000200db64bbde0] c0000000003f8f04 SyS_ioctl+0xc4/0x130 [c000200db64bbe30] c00000000000b184 system_call+0x58/0x6c When there is no room to send the I/O request, the cached room is refreshed by reading the memory mapped command room value from the AFU. The AFU register mapping is refreshed during a reset, creating a race condition that can lead to the Oops above. During a device reset, the AFU should not be unmapped until all the active send threads quiesce. An atomic counter, cmds_active, is currently used to track internal AFU commands and quiesce during reset. This same counter can also be used for the active send threads. Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com> --- drivers/scsi/cxlflash/main.c | 2 ++ 1 file changed, 2 insertions(+)