On Mon, Nov 24, 2014 at 03:16:19PM +0100, Heiko Carstens wrote:
> While debugging some "sleeping function called from invalid context" bug I
> realized that the debug message "Preemption disabled at:" pointed to an
> incorrect function.
> In particular if the function/action that disabled preemption was
> spin_lock_bh() then current->preempt_disable_ip won't be updated.
>
> The reason for this is that __local_bh_disable_ip() will increase
> preempt_count manually instead of calling preempt_count_add(), which
> would handle the update correctly.
> It look like the manual handling was done to work around some lockdep issue.
>
> So add the missing update of current->preempt_disable_ip to
> __local_bh_disable_ip() as well.
>
> Signed-off-by: Heiko Carstens <heiko.carst...@de.ibm.com>
> ---
> kernel/softirq.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 501baa9ac1be..edd51027e3ab 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -114,8 +114,13 @@ void __local_bh_disable_ip(unsigned long ip, unsigned
> int cnt)
> trace_softirqs_off(ip);
> raw_local_irq_restore(flags);
>
> - if (preempt_count() == cnt)
> - trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
> + if (preempt_count() == cnt) {
> + unsigned long ip = get_parent_ip(CALLER_ADDR1);
> +#ifdef CONFIG_DEBUG_PREEMPT
> + current->preempt_disable_ip = ip;
> +#endif
> + trace_preempt_off(CALLER_ADDR0, ip);
> + }
> }
> EXPORT_SYMBOL(__local_bh_disable_ip);
> #endif /* CONFIG_TRACE_IRQFLAGS */
*ping*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
