| Message ID | 20230505113315.3307723-5-liujian56@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fix softlockup in run_timer_softirq | expand |
On Fri, May 5, 2023 at 1:24 PM Liu Jian <liujian56@huawei.com> wrote: > > From: Peter Zijlstra <peterz@infradead.org> > > Allow terminating the softirq processing loop without finishing the > vectors. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Signed-off-by: Liu Jian <liujian56@huawei.com> > --- > kernel/softirq.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/kernel/softirq.c b/kernel/softirq.c > index 48a81d8ae49a..e2cad5d108c8 100644 > --- a/kernel/softirq.c > +++ b/kernel/softirq.c > @@ -582,6 +582,9 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) > prev_count, preempt_count()); > preempt_count_set(prev_count); > } > + > + if (pending && __softirq_needs_break(start)) > + break; This means that some softirq may starve, because for_each_set_bit(vec_nr, &pending, NR_SOFTIRQS) Always iterate using the same order (of bits) > } > > if (!IS_ENABLED(CONFIG_PREEMPT_RT) && > @@ -590,13 +593,14 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) > > local_irq_disable(); > > - pending = local_softirq_pending(); > - if (pending) { > - if (!__softirq_needs_break(start) && --max_restart) > - goto restart; > + if (pending) > + or_softirq_pending(pending); > + else if ((pending = local_softirq_pending()) && > + !__softirq_needs_break(start) && > + --max_restart) > + goto restart; > > - wakeup_softirqd(); > - } > + wakeup_softirqd(); > > account_softirq_exit(current); > lockdep_softirq_end(in_hardirq); > -- > 2.34.1 >
On 2023/5/5 20:10, Eric Dumazet wrote: > On Fri, May 5, 2023 at 1:24 PM Liu Jian <liujian56@huawei.com> wrote: >> >> From: Peter Zijlstra <peterz@infradead.org> >> >> Allow terminating the softirq processing loop without finishing the >> vectors. >> >> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >> Signed-off-by: Liu Jian <liujian56@huawei.com> >> --- >> kernel/softirq.c | 16 ++++++++++------ >> 1 file changed, 10 insertions(+), 6 deletions(-) >> >> diff --git a/kernel/softirq.c b/kernel/softirq.c >> index 48a81d8ae49a..e2cad5d108c8 100644 >> --- a/kernel/softirq.c >> +++ b/kernel/softirq.c >> @@ -582,6 +582,9 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) >> prev_count, preempt_count()); >> preempt_count_set(prev_count); >> } >> + >> + if (pending && __softirq_needs_break(start)) >> + break; > > This means that some softirq may starve, because > > for_each_set_bit(vec_nr, &pending, NR_SOFTIRQS) > > Always iterate using the same order (of bits) > > Yes, we need to record the softirq that is not executed and continue next time. I will fix it in next version. Thanks. > > >> } >> >> if (!IS_ENABLED(CONFIG_PREEMPT_RT) && >> @@ -590,13 +593,14 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) >> >> local_irq_disable(); >> >> - pending = local_softirq_pending(); >> - if (pending) { >> - if (!__softirq_needs_break(start) && --max_restart) >> - goto restart; >> + if (pending) >> + or_softirq_pending(pending); >> + else if ((pending = local_softirq_pending()) && >> + !__softirq_needs_break(start) && >> + --max_restart) >> + goto restart; >> >> - wakeup_softirqd(); >> - } >> + wakeup_softirqd(); >> >> account_softirq_exit(current); >> lockdep_softirq_end(in_hardirq); >> -- >> 2.34.1 >>
diff --git a/kernel/softirq.c b/kernel/softirq.c index 48a81d8ae49a..e2cad5d108c8 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -582,6 +582,9 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) prev_count, preempt_count()); preempt_count_set(prev_count); } + + if (pending && __softirq_needs_break(start)) + break; } if (!IS_ENABLED(CONFIG_PREEMPT_RT) && @@ -590,13 +593,14 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) local_irq_disable(); - pending = local_softirq_pending(); - if (pending) { - if (!__softirq_needs_break(start) && --max_restart) - goto restart; + if (pending) + or_softirq_pending(pending); + else if ((pending = local_softirq_pending()) && + !__softirq_needs_break(start) && + --max_restart) + goto restart; - wakeup_softirqd(); - } + wakeup_softirqd(); account_softirq_exit(current); lockdep_softirq_end(in_hardirq);