Tushar Behera wrote:
>
> The spinlock clocks_lock can be held during ISR, hence it is not safe to
> hold that lock with disabling interrupts.
>
> It fixes following potential deadlock.
>
> =========================================================
> [ INFO: possible irq lock inversion dependency detected ]
> 3.6.0-rc4+ #2 Not tainted
> ---------------------------------------------------------
> swapper/0/1 just changed the state of lock:
> (&(&host->lock)->rlock){-.....}, at: [<c027fb0d>] sdhci_irq+0x15/0x564
> but this lock took another, HARDIRQ-unsafe lock in the past:
> (clocks_lock){+.+...}
>
> and interrupts could create inverse lock ordering between them.
>
> other info that might help us debug this:
> Possible interrupt unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(clocks_lock);
> local_irq_disable();
> lock(&(&host->lock)->rlock);
> lock(clocks_lock);
> <Interrupt>
> lock(&(&host->lock)->rlock);
>
> *** DEADLOCK ***
>
> Signed-off-by: Tushar Behera <tushar.behera@xxxxxxxxxx>
> ---
> arch/arm/plat-samsung/clock.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c
> index 65c5eca..9b71719 100644
> --- a/arch/arm/plat-samsung/clock.c
> +++ b/arch/arm/plat-samsung/clock.c
> @@ -144,6 +144,7 @@ long clk_round_rate(struct clk *clk, unsigned long
> rate)
>
> int clk_set_rate(struct clk *clk, unsigned long rate)
> {
> + unsigned long flags;
> int ret;
>
> if (IS_ERR(clk))
> @@ -159,9 +160,9 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
> if (clk->ops == NULL || clk->ops->set_rate == NULL)
> return -EINVAL;
>
> - spin_lock(&clocks_lock);
> + spin_lock_irqsave(&clocks_lock, flags);
> ret = (clk->ops->set_rate)(clk, rate);
> - spin_unlock(&clocks_lock);
> + spin_unlock_irqrestore(&clocks_lock, flags);
>
> return ret;
> }
> --
> 1.7.4.1
Looks OK, applied.
Thanks.
Best regards,
Kgene.
--
Kukjin Kim <kgene.kim@xxxxxxxxxxx>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.
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