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 <[email protected]> know about it.
>From [email protected] Sat Oct 17 13:59:05 2015
From: Dave Martin <[email protected]>
Date: Fri, 24 Jul 2015 17:39:21 +0100
Subject: [PATCH REPOST] serial/amba-pl011: Disable interrupts around TX softirq
To: [email protected], Greg Kroah-Hartman
<[email protected]>
Cc: Russell King <[email protected]>, Robin Murphy <[email protected]>,
[email protected], Jakub Kiciński <[email protected]>, Andrew
Jackson <[email protected]>, Graeme Gregory <[email protected]>, Andre
Przywara <[email protected]>, Jorge Ramirez-Ortiz
<[email protected]>, popcorn mix <[email protected]>, stable
<[email protected]>
Message-ID: <[email protected]>
From: Dave Martin <[email protected]>
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 <[email protected]>
Tested-by: Robin Murphy <[email protected]>
Tested-by: Stefan Wahren <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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 [email protected] are
queue-4.1/serial-amba-pl011-disable-interrupts-around-tx-softirq.patch
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