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| author | Dave Martin <Dave.Martin@arm.com> | 2015-07-24 17:39:21 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-22 14:43:20 -0700 |
| commit | 66196fff4dddb5ff617b45f991f83a25f7629e1f (patch) | |
| tree | 2163200d48eec3a6df8cc567a8ce933db5a6632e | |
| parent | c04b33c93dc0c566b02ac573528bb82ac6065666 (diff) | |
| download | lwn-66196fff4dddb5ff617b45f991f83a25f7629e1f.tar.gz lwn-66196fff4dddb5ff617b45f991f83a25f7629e1f.zip | |
serial/amba-pl011: Disable interrupts around TX softirq
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@arm.com>
Tested-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 763eb20fe321..0cc622afb67d 100644 --- 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 *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) |