• Tushar Behera's avatar
    ARM: SAMSUNG: Use spin_lock_{irqsave,irqrestore} in clk_set_rate · d6838a62
    Tushar Behera authored
    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: default avatarTushar Behera <tushar.behera@linaro.org>
    Signed-off-by: default avatarKukjin Kim <kgene.kim@samsung.com>
    d6838a62
clock.c 9.68 KB