This is a note to let you know that I've just added the patch titled
[PATCH REPOST] serial/amba-pl011: Disable interrupts around TX softirq
to the 4.1-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:
serial-amba-pl011-disable-interrupts-around-tx-softirq.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From Dave.Martin@xxxxxxx Sat Oct 17 13:59:05 2015
From: Dave Martin <Dave.Martin@xxxxxxx>
Date: Fri, 24 Jul 2015 17:39:21 +0100
Subject: [PATCH REPOST] serial/amba-pl011: Disable interrupts around TX softirq
To: linux-serial@xxxxxxxxxxxxxxx, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>, Robin Murphy <Robin.Murphy@xxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, Jakub Kiciński <moorray3@xxxxx>, Andrew Jackson <Andrew.Jackson@xxxxxxx>, Graeme Gregory <gg@xxxxxxxxxxxxxxx>, Andre Przywara <Andre.Przywara@xxxxxxx>, Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>, popcorn mix <popcornmix@xxxxxxxxx>, stable <stable@xxxxxxxxxxxxxxx>
Message-ID: <1437755961-15403-1-git-send-email-Dave.Martin@xxxxxxx>
From: Dave Martin <Dave.Martin@xxxxxxx>
pl011_tx_softirq() currently uses spin_{,un}lock(), which are not
sufficient to inhibit pl011_int() from being triggered by a local
IRQ and trying to re-take the same lock. This can lead to
deadlocks.
This patch uses the _irq() locking variants instead to ensure that
pl011_int() handling for a given port is deferred until any
pl011_tx_softirq() work for that port is complete.
Notes for stable:
This patch fixes an issue that is fixed by the following upstream
commit, which is a more substantial rewrite of the affected code,
fixing multiple, mostly more minor issues:
1e84d22322ceed4767db1e5342c830dd60c8210f
serial/amba-pl011: Refactor and simplify TX FIFO handling
The upstream patch was rejected for stable on the reasonable grounds
that it was too big and complex a patch. The original buggy code was
merged in v4.1, and the rewrite was merged in v4.2, leaving only v4.1
affected.
This patch replaces the 1e84d22, for 4.1.x only.
Fixes: 734745caeb9f serial/amba-pl011: Activate TX IRQ passively
Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
Tested-by: Robin Murphy <robin.murphy@xxxxxxx>
Tested-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1360,9 +1360,9 @@ static void pl011_tx_softirq(struct work
struct uart_amba_port *uap =
container_of(dwork, struct uart_amba_port, tx_softirq_work);
- spin_lock(&uap->port.lock);
+ spin_lock_irq(&uap->port.lock);
while (pl011_tx_chars(uap)) ;
- spin_unlock(&uap->port.lock);
+ spin_unlock_irq(&uap->port.lock);
}
static void pl011_tx_irq_seen(struct uart_amba_port *uap)
Patches currently in stable-queue which might be from Dave.Martin@xxxxxxx are
queue-4.1/serial-amba-pl011-disable-interrupts-around-tx-softirq.patch
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