This is a note to let you know that I've just added the patch titled
cw1200: Prevent a lock-related hang in the cw1200_spi driver
to the 3.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cw1200-prevent-a-lock-related-hang-in-the-cw1200_spi-driver.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 85ba8f529c57ac6e2fca9be0d9e17920a1afb2e8 Mon Sep 17 00:00:00 2001
From: Solomon Peachy <pizza@xxxxxxxxxxxx>
Date: Tue, 27 Aug 2013 20:29:47 -0400
Subject: cw1200: Prevent a lock-related hang in the cw1200_spi driver
From: Solomon Peachy <pizza@xxxxxxxxxxxx>
commit 85ba8f529c57ac6e2fca9be0d9e17920a1afb2e8 upstream.
The cw1200_spi driver tries to mirror the cw1200_sdio driver's lock
API, which relies on sdio_claim_host/sdio_release_host to serialize
hardware operations across multiple threads.
Unfortunately the implementation was flawed, as it lacked a way to wake
up the lock requestor when there was contention, often resulting in a
hang.
This problem was uncovered while trying to fix the
spi-transfers-in-interrupt-context BUG() corrected in the previous
patch. Many thanks to Dave Sizeburns for his assistance in fixing this.
Signed-off-by: Solomon Peachy <pizza@xxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/wireless/cw1200/cw1200_spi.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/drivers/net/wireless/cw1200/cw1200_spi.c
+++ b/drivers/net/wireless/cw1200/cw1200_spi.c
@@ -40,6 +40,7 @@ struct hwbus_priv {
struct cw1200_common *core;
const struct cw1200_platform_data_spi *pdata;
spinlock_t lock; /* Serialize all bus operations */
+ wait_queue_head_t wq;
int claimed;
};
@@ -197,8 +198,11 @@ static void cw1200_spi_lock(struct hwbus
{
unsigned long flags;
+ DECLARE_WAITQUEUE(wait, current);
+
might_sleep();
+ add_wait_queue(&self->wq, &wait);
spin_lock_irqsave(&self->lock, flags);
while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
@@ -211,6 +215,7 @@ static void cw1200_spi_lock(struct hwbus
set_current_state(TASK_RUNNING);
self->claimed = 1;
spin_unlock_irqrestore(&self->lock, flags);
+ remove_wait_queue(&self->wq, &wait);
return;
}
@@ -222,6 +227,8 @@ static void cw1200_spi_unlock(struct hwb
spin_lock_irqsave(&self->lock, flags);
self->claimed = 0;
spin_unlock_irqrestore(&self->lock, flags);
+ wake_up(&self->wq);
+
return;
}
@@ -400,6 +407,8 @@ static int cw1200_spi_probe(struct spi_d
spi_set_drvdata(func, self);
+ init_waitqueue_head(&self->wq);
+
status = cw1200_spi_irq_subscribe(self);
status = cw1200_core_probe(&cw1200_spi_hwbus_ops,
Patches currently in stable-queue which might be from pizza@xxxxxxxxxxxx are
queue-3.11/cw1200-prevent-a-lock-related-hang-in-the-cw1200_spi-driver.patch
queue-3.11/cw1200-don-t-perform-spi-transfers-in-interrupt-context.patch
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