[3.13.y.z extended stable] Patch "libata: introduce ata_host->n_tags to avoid oops on SAS controllers" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Thu Aug 7 21:55:35 UTC 2014
This is a note to let you know that I have just added a patch titled
libata: introduce ata_host->n_tags to avoid oops on SAS controllers
to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue
This patch is scheduled to be released in version 3.13.11.6.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From f5a26d6a9117b86c42256b8e75e929a3aff656ba Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj at kernel.org>
Date: Wed, 23 Jul 2014 09:05:27 -0400
Subject: libata: introduce ata_host->n_tags to avoid oops on SAS controllers
commit 1a112d10f03e83fb3a2fdc4c9165865dec8a3ca6 upstream.
1871ee134b73 ("libata: support the ata host which implements a queue
depth less than 32") directly used ata_port->scsi_host->can_queue from
ata_qc_new() to determine the number of tags supported by the host;
unfortunately, SAS controllers doing SATA don't initialize ->scsi_host
leading to the following oops.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
IP: [<ffffffff814e0618>] ata_qc_new_init+0x188/0x1b0
PGD 0
Oops: 0002 [#1] SMP
Modules linked in: isci libsas scsi_transport_sas mgag200 drm_kms_helper ttm
CPU: 1 PID: 518 Comm: udevd Not tainted 3.16.0-rc6+ #62
Hardware name: Intel Corporation S2600CO/S2600CO, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
task: ffff880c1a00b280 ti: ffff88061a000000 task.ti: ffff88061a000000
RIP: 0010:[<ffffffff814e0618>] [<ffffffff814e0618>] ata_qc_new_init+0x188/0x1b0
RSP: 0018:ffff88061a003ae8 EFLAGS: 00010012
RAX: 0000000000000001 RBX: ffff88000241ca80 RCX: 00000000000000fa
RDX: 0000000000000020 RSI: 0000000000000020 RDI: ffff8806194aa298
RBP: ffff88061a003ae8 R08: ffff8806194a8000 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88000241ca80 R12: ffff88061ad58200
R13: ffff8806194aa298 R14: ffffffff814e67a0 R15: ffff8806194a8000
FS: 00007f3ad7fe3840(0000) GS:ffff880627620000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000058 CR3: 000000061a118000 CR4: 00000000001407e0
Stack:
ffff88061a003b20 ffffffff814e96e1 ffff88000241ca80 ffff88061ad58200
ffff8800b6bf6000 ffff880c1c988000 ffff880619903850 ffff88061a003b68
ffffffffa0056ce1 ffff88061a003b48 0000000013d6e6f8 ffff88000241ca80
Call Trace:
[<ffffffff814e96e1>] ata_sas_queuecmd+0xa1/0x430
[<ffffffffa0056ce1>] sas_queuecommand+0x191/0x220 [libsas]
[<ffffffff8149afee>] scsi_dispatch_cmd+0x10e/0x300
[<ffffffff814a3bc5>] scsi_request_fn+0x2f5/0x550
[<ffffffff81317613>] __blk_run_queue+0x33/0x40
[<ffffffff8131781a>] queue_unplugged+0x2a/0x90
[<ffffffff8131ceb4>] blk_flush_plug_list+0x1b4/0x210
[<ffffffff8131d274>] blk_finish_plug+0x14/0x50
[<ffffffff8117eaa8>] __do_page_cache_readahead+0x198/0x1f0
[<ffffffff8117ee21>] force_page_cache_readahead+0x31/0x50
[<ffffffff8117ee7e>] page_cache_sync_readahead+0x3e/0x50
[<ffffffff81172ac6>] generic_file_read_iter+0x496/0x5a0
[<ffffffff81219897>] blkdev_read_iter+0x37/0x40
[<ffffffff811e307e>] new_sync_read+0x7e/0xb0
[<ffffffff811e3734>] vfs_read+0x94/0x170
[<ffffffff811e43c6>] SyS_read+0x46/0xb0
[<ffffffff811e33d1>] ? SyS_lseek+0x91/0xb0
[<ffffffff8171ee29>] system_call_fastpath+0x16/0x1b
Code: 00 00 00 88 50 29 83 7f 08 01 19 d2 83 e2 f0 83 ea 50 88 50 34 c6 81 1d 02 00 00 40 c6 81 17 02 00 00 00 5d c3 66 0f 1f 44 00 00 <89> 14 25 58 00 00 00
Fix it by introducing ata_host->n_tags which is initialized to
ATA_MAX_QUEUE - 1 in ata_host_init() for SAS controllers and set to
scsi_host_template->can_queue in ata_host_register() for !SAS ones.
As SAS hosts are never registered, this will give them the same
ATA_MAX_QUEUE - 1 as before. Note that we can't use
scsi_host->can_queue directly for SAS hosts anyway as they can go
higher than the libata maximum.
Signed-off-by: Tejun Heo <tj at kernel.org>
Reported-by: Mike Qiu <qiudayu at linux.vnet.ibm.com>
Reported-by: Jesse Brandeburg <jesse.brandeburg at gmail.com>
Reported-by: Peter Hurley <peter at hurleysoftware.com>
Reported-by: Peter Zijlstra <peterz at infradead.org>
Tested-by: Alexey Kardashevskiy <aik at ozlabs.ru>
Fixes: 1871ee134b73 ("libata: support the ata host which implements a queue depth less than 32")
Cc: Kevin Hao <haokexin at gmail.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
drivers/ata/libata-core.c | 16 ++++------------
include/linux/libata.h | 1 +
2 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 0172e30..f761603 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4798,9 +4798,8 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
{
struct ata_queued_cmd *qc = NULL;
- unsigned int i, tag, max_queue;
-
- max_queue = ap->scsi_host->can_queue;
+ unsigned int max_queue = ap->host->n_tags;
+ unsigned int i, tag;
/* no command while frozen */
if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
@@ -6109,6 +6108,7 @@ void ata_host_init(struct ata_host *host, struct device *dev,
{
spin_lock_init(&host->lock);
mutex_init(&host->eh_mutex);
+ host->n_tags = ATA_MAX_QUEUE - 1;
host->dev = dev;
host->ops = ops;
}
@@ -6190,15 +6190,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
{
int i, rc;
- /*
- * The max queue supported by hardware must not be greater than
- * ATA_MAX_QUEUE.
- */
- if (sht->can_queue > ATA_MAX_QUEUE) {
- dev_err(host->dev, "BUG: the hardware max queue is too large\n");
- WARN_ON(1);
- return -EINVAL;
- }
+ host->n_tags = clamp(sht->can_queue, 1, ATA_MAX_QUEUE - 1);
/* host must have been started */
if (!(host->flags & ATA_HOST_STARTED)) {
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3fee55e..e13b3ae 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -593,6 +593,7 @@ struct ata_host {
struct device *dev;
void __iomem * const *iomap;
unsigned int n_ports;
+ unsigned int n_tags; /* nr of NCQ tags */
void *private_data;
struct ata_port_operations *ops;
unsigned long flags;
--
1.9.1
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