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ANDROID: Revert "Mark HI and TASKLET softirq synchronous"

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This reverts commit 3c53776e29 because it
makes HI_SOFTIRQ and TASKLET_SOFTIRQ run immediately i.e. not get
deferred to ksfotirqd. The commit text calls out that this is a stopgap
until a better solution is deviced and that it should have included
TIMER_SOFTIRQ as well, but chose not to.

Patch ebc7b75d772647813cdaf085c7f5adf3c90b033b from Qualcomm is a more
comprehensive solution which defers long running tasklets to ksfotirqd
when a rt task is interrupted.

We cannot use both these together as they conflict; e.g. the original
makes TASKLET softirq run immediately while the Qualcomm one defers it
if rt gets interrupted. Choose to use the Qualcomm one.

Bug: 168521633
Change-Id: I4af64cd7e2c4291dda5f503bf2d74ede459a76c6
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
[elavila: port to mainline, resolve conflicts, add commit text]
Signed-off-by: J. Avila <elavila@google.com>
This commit is contained in:
Satya Durga Srinivasu Prabhala
2019-01-08 15:38:32 -08:00
committed by J. Avila
parent 0578248bed
commit ea05d25c78
1 changed files with 4 additions and 8 deletions
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12
kernel/softirq.c
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@@ -85,16 +85,12 @@ static void wakeup_softirqd(void)
/* /*
* If ksoftirqd is scheduled, we do not want to process pending softirqs * If ksoftirqd is scheduled, we do not want to process pending softirqs
* right now. Let ksoftirqd handle this at its own rate, to get fairness, * right now. Let ksoftirqd handle this at its own rate, to get fairness.
* unless we're doing some of the synchronous softirqs.
*/ */
#define SOFTIRQ_NOW_MASK ((1 << HI_SOFTIRQ) | (1 << TASKLET_SOFTIRQ)) static bool ksoftirqd_running(void)
static bool ksoftirqd_running(unsigned long pending)
{ {
struct task_struct *tsk = __this_cpu_read(ksoftirqd); struct task_struct *tsk = __this_cpu_read(ksoftirqd);
if (pending & SOFTIRQ_NOW_MASK)
return false;
return tsk && (tsk->state == TASK_RUNNING) && return tsk && (tsk->state == TASK_RUNNING) &&
!__kthread_should_park(tsk); !__kthread_should_park(tsk);
} }
@@ -363,7 +359,7 @@ asmlinkage __visible void do_softirq(void)
pending = local_softirq_pending(); pending = local_softirq_pending();
if (pending && !ksoftirqd_running(pending)) if (pending && !ksoftirqd_running())
do_softirq_own_stack(); do_softirq_own_stack();
local_irq_restore(flags); local_irq_restore(flags);
@@ -397,7 +393,7 @@ void irq_enter(void)
static inline void invoke_softirq(void) static inline void invoke_softirq(void)
{ {
if (ksoftirqd_running(local_softirq_pending())) if (ksoftirqd_running())
return; return;
if (!force_irqthreads) { if (!force_irqthreads) {