When SCSI EH invokes zFCP's callbacks for eh_device_reset_handler() and
eh_target_reset_handler(), it expects us to relent the ownership over
the given scsi_cmnd and all other scsi_cmnds within the same scope - LUN
or target - when returning with SUCCESS from the callback ('release'
them). SCSI EH can then reuse those commands.
We did not follow this rule to release commands upon SUCCESS; and if
later a reply arrived for one of those supposed to be released commands,
we would still make use of the scsi_cmnd in our ingress tasklet. This
will at least result in undefined behavior or a kernel panic because of
a wrong kernel pointer dereference.
To fix this, we NULLify all pointers to scsi_cmnds (struct zfcp_fsf_req
*)->data in the matching scope if a TMF was successful. This is done
under the locks (struct zfcp_adapter *)->abort_lock and (struct
zfcp_reqlist *)->lock to prevent the requests from being removed from
the request-hashtable, and the ingress tasklet from making use of the
scsi_cmnd-pointer in zfcp_fsf_fcp_cmnd_handler().
For cases where a reply arrives during SCSI EH, but before we get a
chance to NULLify the pointer - but before we return from the callback
-, we assume that the code is protected from races via the CAS operation
in blk_complete_request() that is called in scsi_done().
The following stacktrace shows an example for a crash resulting from the
previous behavior:
Unable to handle kernel pointer dereference at virtual kernel address fffffee17a672000
Oops: 0038 [#1] SMP
CPU: 2 PID: 0 Comm: swapper/2 Not tainted
task: 00000003f7ff5be0 ti: 00000003f3d38000 task.ti: 00000003f3d38000
Krnl PSW : 0404d00180000000 00000000001156b0 (smp_vcpu_scheduled+0x18/0x40)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3
Krnl GPRS: 000000200000007e 0000000000000000 fffffee17a671fd8 0000000300000015
ffffffff80000000 00000000005dfde8 07000003f7f80e00 000000004fa4e800
000000036ce8d8f8 000000036ce8d9c0 00000003ece8fe00 ffffffff969c9e93
00000003fffffffd 000000036ce8da10 00000000003bf134 00000003f3b07918
Krnl Code: 00000000001156a2: a7190000 lghi %r1,0
00000000001156a6: a7380015 lhi %r3,21
#00000000001156aa: e32050000008 ag %r2,0(%r5)
>00000000001156b0: 482022b0 lh %r2,688(%r2)
00000000001156b4: ae123000 sigp %r1,%r2,0(%r3)
00000000001156b8: b2220020 ipm %r2
00000000001156bc: 8820001c srl %r2,28
00000000001156c0: c02700000001 xilf %r2,1
Call Trace:
([<0000000000000000>] 0x0)
[<000003ff807bdb8e>] zfcp_fsf_fcp_cmnd_handler+0x3de/0x490 [zfcp]
[<000003ff807be30a>] zfcp_fsf_req_complete+0x252/0x800 [zfcp]
[<000003ff807c0a48>] zfcp_fsf_reqid_check+0xe8/0x190 [zfcp]
[<000003ff807c194e>] zfcp_qdio_int_resp+0x66/0x188 [zfcp]
[<000003ff80440c64>] qdio_kick_handler+0xdc/0x310 [qdio]
[<000003ff804463d0>] __tiqdio_inbound_processing+0xf8/0xcd8 [qdio]
[<0000000000141fd4>] tasklet_action+0x9c/0x170
[<0000000000141550>] __do_softirq+0xe8/0x258
[<000000000010ce0a>] do_softirq+0xba/0xc0
[<000000000014187c>] irq_exit+0xc4/0xe8
[<000000000046b526>] do_IRQ+0x146/0x1d8
[<00000000005d6a3c>] io_return+0x0/0x8
[<00000000005d6422>] vtime_stop_cpu+0x4a/0xa0
([<0000000000000000>] 0x0)
[<0000000000103d8a>] arch_cpu_idle+0xa2/0xb0
[<0000000000197f94>] cpu_startup_entry+0x13c/0x1f8
[<0000000000114782>] smp_start_secondary+0xda/0xe8
[<00000000005d6efe>] restart_int_handler+0x56/0x6c
[<0000000000000000>] 0x0
Last Breaking-Event-Address:
[<00000000003bf12e>] arch_spin_lock_wait+0x56/0xb0
Suggested-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Fixes: ea127f9754 ("[PATCH] s390 (7/7): zfcp host adapter.") (tglx/history.git)
Cc: <stable@vger.kernel.org> #2.6.32+
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.
Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Move the code for tracking FSF requests to new file to have this code
in one place. The functions for adding and removing requests on the
I/O path are already inline. The alloc and free functions are only
called once, so it does not hurt to inline them and add them to the
same file.
Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
