* Re: [PATCH 3/12] drivers/char/amiserial.c: Add missing local_irq_restore
2010-03-29 15:34 [PATCH 3/12] drivers/char/amiserial.c: Add missing local_irq_restore Julia Lawall
@ 2010-04-01 19:51 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2010-04-01 19:51 UTC (permalink / raw)
To: Julia Lawall; +Cc: linux-kernel, kernel-janitors
On Mon, 29 Mar 2010 17:34:11 +0200 (CEST)
Julia Lawall <julia@diku.dk> wrote:
> From: Julia Lawall <julia@diku.dk>
>
> Add local_irq_restore after the labels that can be reached after a
> local_irq_save.
>
> A simplified version of the semantic patch that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @r exists@
> expression E1;
> identifier f;
> @@
>
> f (...) { <+...
> * local_irq_save (E1,...);
> ... when != E1
> * return ...;
> ...+> }
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@diku.dk>
>
> ---
> drivers/char/amiserial.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
> index 6c32fbf..2131ecb 100644
> --- a/drivers/char/amiserial.c
> +++ b/drivers/char/amiserial.c
> @@ -2056,6 +2056,7 @@ fail_free_irq:
> free_irq(IRQ_AMIGA_TBE, state);
> fail_unregister:
> tty_unregister_driver(serial_driver);
> + local_irq_restore(flags);
> fail_release_mem_region:
> release_mem_region(CUSTOM_PHYSADDR+0x30, 4);
> fail_put_tty_driver:
We shouldn't be calling tty_unregister_driver() with local interrupts
disabled - it does mutex_lock() (at least), which will emit a
might_sleep() warning (at least).
I don't expect there was any need to disable irq's across the
request_irq() calls (?), hence:
From: Julia Lawall <julia@diku.dk>
rs_init() is failing to restore interrupts on two error paths, and is
incorrectly calling tty_unregister_driver() with local interrupts
disabled.
Fix these things by disabling interrupts later, after the reauest_irq()
calls.
A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
expression E1;
identifier f;
@@
f (...) { <+...
* local_irq_save (E1,...);
... when != E1
* return ...;
...+> }
// </smpl>
[akpm@linux-foundation.org: reimplement the fix]
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
drivers/char/amiserial.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN drivers/char/amiserial.c~drivers-char-amiserialc-add-missing-local_irq_restore drivers/char/amiserial.c
--- a/drivers/char/amiserial.c~drivers-char-amiserialc-add-missing-local_irq_restore
+++ a/drivers/char/amiserial.c
@@ -2021,8 +2021,6 @@ static int __init rs_init(void)
state->baud_base = amiga_colorclock;
state->xmit_fifo_size = 1;
- local_irq_save(flags);
-
/* set ISRs, and then disable the rx interrupts */
error = request_irq(IRQ_AMIGA_TBE, ser_tx_int, 0, "serial TX", state);
if (error)
@@ -2033,6 +2031,8 @@ static int __init rs_init(void)
if (error)
goto fail_free_irq;
+ local_irq_save(flags);
+
/* turn off Rx and Tx interrupts */
custom.intena = IF_RBF | IF_TBE;
mb();
_
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