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SubjectRe: [PATCH] pstore: avoid recursive spinlocks in the oops_in_progress case
On Tue, Sep 18, 2012 at 01:43:44AM +0800, Chuansheng Liu wrote:
> Like 8250 driver, when pstore is registered as a console,
> to avoid recursive spinlocks when panic happening, change the
> spin_lock_irqsave to spin_trylock_irqsave when oops_in_progress
> is true.
>
> Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
> ---
> fs/pstore/platform.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 29996e8..cbcb5fc 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -164,7 +164,12 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
>
> if (c > psinfo->bufsize)
> c = psinfo->bufsize;
> - spin_lock_irqsave(&psinfo->buf_lock, flags);
> +
> + if (oops_in_progress) {
> + if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
> + break;

Mm... why break?

Like 8250, in this case it's better still log the console.
That is, something along these lines:

bool locked = 1;

if (oops_in_progress)
locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
else
spin_lock_irqsave(&psinfo->buf_lock, flags);

memcpy(psinfo->buf, s, c);
psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);

if (locked)
spin_unlock_irqrestore(&psinfo->buf_lock, flags);


Thanks,

Anton.

> + } else
> + spin_lock_irqsave(&psinfo->buf_lock, flags);
> memcpy(psinfo->buf, s, c);
> psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
> spin_unlock_irqrestore(&psinfo->buf_lock, flags);
> --
> 1.7.0.4


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