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Date: Wed, 11 Nov 2009 13:35:22 +0900 From: Jupyung Lee <jupyung@...il.com> To: LKML <linux-kernel@...r.kernel.org> Cc: Thomas Gleixner <tglx@...utronix.de>, Jupyung Lee <jupyung@...il.com> Subject: [PATCH-rt 1/1] softirqs: add preempt_check_resched() in ksoftirqd() 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@...il.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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