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Subject[PATCH 42/58] sata_fsl: save irqs while coalescing
Date
3.5.7.21 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anthony Foiani <anthony.foiani@gmail.com>

commit 99bbdfa6bdcb4bdf5be914a48e9b46941bf30819 upstream.

Before this patch, I was seeing the following lockdep splat on my
MPC8315 (PPC32) target:

[ 9.086051] =================================
[ 9.090393] [ INFO: inconsistent lock state ]
[ 9.094744] 3.9.7-ajf-gc39503d #1 Not tainted
[ 9.099087] ---------------------------------
[ 9.103432] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
[ 9.109431] scsi_eh_1/39 [HC1[1]:SC0[0]:HE0:SE1] takes:
[ 9.114642] (&(&host->lock)->rlock){?.+...}, at: [<c02f4168>] sata_fsl_interrupt+0x50/0x250
[ 9.123137] {HARDIRQ-ON-W} state was registered at:
[ 9.128004] [<c006cdb8>] lock_acquire+0x90/0xf4
[ 9.132737] [<c043ef04>] _raw_spin_lock+0x34/0x4c
[ 9.137645] [<c02f3560>] fsl_sata_set_irq_coalescing+0x68/0x100
[ 9.143750] [<c02f36a0>] sata_fsl_init_controller+0xa8/0xc0
[ 9.149505] [<c02f3f10>] sata_fsl_probe+0x17c/0x2e8
[ 9.154568] [<c02acc90>] driver_probe_device+0x90/0x248
[ 9.159987] [<c02acf0c>] __driver_attach+0xc4/0xc8
[ 9.164964] [<c02aae74>] bus_for_each_dev+0x5c/0xa8
[ 9.170028] [<c02ac218>] bus_add_driver+0x100/0x26c
[ 9.175091] [<c02ad638>] driver_register+0x88/0x198
[ 9.180155] [<c0003a24>] do_one_initcall+0x58/0x1b4
[ 9.185226] [<c05aeeac>] kernel_init_freeable+0x118/0x1c0
[ 9.190823] [<c0004110>] kernel_init+0x18/0x108
[ 9.195542] [<c000f6b8>] ret_from_kernel_thread+0x64/0x6c
[ 9.201142] irq event stamp: 160
[ 9.204366] hardirqs last enabled at (159): [<c043f778>] _raw_spin_unlock_irq+0x30/0x50
[ 9.212469] hardirqs last disabled at (160): [<c000f414>] reenable_mmu+0x30/0x88
[ 9.219867] softirqs last enabled at (144): [<c002ae5c>] __do_softirq+0x168/0x218
[ 9.227435] softirqs last disabled at (137): [<c002b0d4>] irq_exit+0xa8/0xb4
[ 9.234481]
[ 9.234481] other info that might help us debug this:
[ 9.240995] Possible unsafe locking scenario:
[ 9.240995]
[ 9.246898] CPU0
[ 9.249337] ----
[ 9.251776] lock(&(&host->lock)->rlock);
[ 9.255878] <Interrupt>
[ 9.258492] lock(&(&host->lock)->rlock);
[ 9.262765]
[ 9.262765] *** DEADLOCK ***
[ 9.262765]
[ 9.268684] no locks held by scsi_eh_1/39.
[ 9.272767]
[ 9.272767] stack backtrace:
[ 9.277117] Call Trace:
[ 9.279589] [cfff9da0] [c0008504] show_stack+0x48/0x150 (unreliable)
[ 9.285972] [cfff9de0] [c0447d5c] print_usage_bug.part.35+0x268/0x27c
[ 9.292425] [cfff9e10] [c006ace4] mark_lock+0x2ac/0x658
[ 9.297660] [cfff9e40] [c006b7e4] __lock_acquire+0x754/0x1840
[ 9.303414] [cfff9ee0] [c006cdb8] lock_acquire+0x90/0xf4
[ 9.308745] [cfff9f20] [c043ef04] _raw_spin_lock+0x34/0x4c
[ 9.314250] [cfff9f30] [c02f4168] sata_fsl_interrupt+0x50/0x250
[ 9.320187] [cfff9f70] [c0079ff0] handle_irq_event_percpu+0x90/0x254
[ 9.326547] [cfff9fc0] [c007a1fc] handle_irq_event+0x48/0x78
[ 9.332220] [cfff9fe0] [c007c95c] handle_level_irq+0x9c/0x104
[ 9.337981] [cfff9ff0] [c000d978] call_handle_irq+0x18/0x28
[ 9.343568] [cc7139f0] [c000608c] do_IRQ+0xf0/0x1a8
[ 9.348464] [cc713a20] [c000fc8c] ret_from_except+0x0/0x14
[ 9.353983] --- Exception: 501 at _raw_spin_unlock_irq+0x40/0x50
[ 9.353983] LR = _raw_spin_unlock_irq+0x30/0x50
[ 9.364839] [cc713af0] [c043db10] wait_for_common+0xac/0x188
[ 9.370513] [cc713b30] [c02ddee4] ata_exec_internal_sg+0x2b0/0x4f0
[ 9.376699] [cc713be0] [c02de18c] ata_exec_internal+0x68/0xa8
[ 9.382454] [cc713c20] [c02de4b8] ata_dev_read_id+0x158/0x594
[ 9.388205] [cc713ca0] [c02ec244] ata_eh_recover+0xd88/0x13d0
[ 9.393962] [cc713d20] [c02f2520] sata_pmp_error_handler+0xc0/0x8ac
[ 9.400234] [cc713dd0] [c02ecdc8] ata_scsi_port_error_handler+0x464/0x5e8
[ 9.407023] [cc713e10] [c02ecfd0] ata_scsi_error+0x84/0xb8
[ 9.412528] [cc713e40] [c02c4974] scsi_error_handler+0xd8/0x47c
[ 9.418457] [cc713eb0] [c004737c] kthread+0xa8/0xac
[ 9.423355] [cc713f40] [c000f6b8] ret_from_kernel_thread+0x64/0x6c

This fix was suggested by Bhushan Bharat <R65777@freescale.com>, and
was discussed in email at:

http://linuxppc.10917.n7.nabble.com/MPC8315-reboot-failure-lockdep-splat-possibly-related-tp75162.html

Same patch successfully tested with 3.9.7. linux-next compiled but
not tested on hardware.

This patch is based off linux-next tag next-20130819
(which is commit 66a01bae29d11916c09f9f5a937cafe7d402e4a5 )

Signed-off-by: Anthony Foiani <anthony.foiani@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[ luis: backported to 3.5: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
drivers/ata/sata_fsl.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index d6577b9..a3f0bbd 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -290,6 +290,7 @@ static void fsl_sata_set_irq_coalescing(struct ata_host *host,
{
struct sata_fsl_host_priv *host_priv = host->private_data;
void __iomem *hcr_base = host_priv->hcr_base;
+ unsigned long flags;

if (count > ICC_MAX_INT_COUNT_THRESHOLD)
count = ICC_MAX_INT_COUNT_THRESHOLD;
@@ -302,12 +303,12 @@ static void fsl_sata_set_irq_coalescing(struct ata_host *host,
(count > ICC_MIN_INT_COUNT_THRESHOLD))
ticks = ICC_SAFE_INT_TICKS;

- spin_lock(&host->lock);
+ spin_lock_irqsave(&host->lock, flags);
iowrite32((count << 24 | ticks), hcr_base + ICC);

intr_coalescing_count = count;
intr_coalescing_ticks = ticks;
- spin_unlock(&host->lock);
+ spin_unlock_irqrestore(&host->lock, flags);

DPRINTK("intrrupt coalescing, count = 0x%x, ticks = %x\n",
intr_coalescing_count, intr_coalescing_ticks);
--
1.8.3.2


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