Messages in this thread Patch in this message | | | From | Jupyung Lee <> | Subject | [PATCH-rt 1/1] softirqs: add preempt_check_resched() in ksoftirqd() | Date | Wed, 11 Nov 2009 13:35:22 +0900 |
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In its current preempt-rt kernel, ksoftirq() includes a series of primitives related with kernel preemption and irq on/off, in the following order:
preempt_disable() ... (1) local_irq_disable() ... (2) __preempt_enable_no_resched() ... (3) local_irq_enable() ... (4)
A problem arises if a process is awakened between (1) and (2) because it is not given a chance to preempt the currently running process for a while since (4): since (4), the kernel is preemptible, but there is no explicit reschedule point.
A simple suggestion to resolve the problem is to add a reschedule point, preempt_check_resched(), just after (4).
Signed-off-by: Jupyung Lee <jupyung@gmail.com> --- kernel/softirq.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c index 590049c..7c1b041 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -1037,6 +1037,7 @@ sleep_more: set_softirq_pending(local_softirq_pending() & ~softirq_mask); local_bh_disable(); local_irq_enable(); + preempt_check_resched(); h = &softirq_vec[data->nr]; if (h) -- 1.5.4.3
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