In order to be able to mix and nest full and per vector softirq masking, we need to be able to track the nesting state using a "full masking" counter and a mask of "individual disabled vectors".
Start with introducing the full masking counter. For now it's a simple mirror of softirq_count() because there is no per vector masking API yet. When this full masking counter is non 0, all softirq vectors are explicitly disabled. Suggested-by: Linus Torvalds <[email protected]> Reviewed-by: David S. Miller <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Cc: Joel Fernandes <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Pavan Kondeti <[email protected]> Cc: Paul E . McKenney <[email protected]> Cc: David S . Miller <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> --- kernel/softirq.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 40aa915c5e4a..2cddaaff3bfa 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -59,6 +59,12 @@ static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp DEFINE_PER_CPU(struct task_struct *, ksoftirqd); +struct softirq_nesting { + unsigned int disabled_all; +}; + +static DEFINE_PER_CPU(struct softirq_nesting, softirq_nesting); + const char * const softirq_to_name[NR_SOFTIRQS] = { "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "IRQ_POLL", "TASKLET", "SCHED", "HRTIMER", "RCU" @@ -120,11 +126,11 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) * call the trace_preempt_off later. */ __preempt_count_add(cnt); - /* - * Were softirqs turned off above: - */ - if (softirq_count() == (cnt & SOFTIRQ_MASK)) + + if (__this_cpu_inc_return(softirq_nesting.disabled_all) == 1) { + softirq_enabled_clear_mask(SOFTIRQ_ALL_MASK); trace_softirqs_off(ip); + } #ifdef CONFIG_TRACE_IRQFLAGS raw_local_irq_restore(flags); @@ -139,6 +145,15 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) } EXPORT_SYMBOL(__local_bh_disable_ip); +static void local_bh_enable_common(unsigned long ip, unsigned int cnt) +{ + if (__this_cpu_dec_return(softirq_nesting.disabled_all)) + return; + + softirq_enabled_set(SOFTIRQ_ALL_MASK); + trace_softirqs_on(ip); +} + static void __local_bh_enable_no_softirq(unsigned int cnt) { lockdep_assert_irqs_disabled(); @@ -146,8 +161,7 @@ static void __local_bh_enable_no_softirq(unsigned int cnt) if (preempt_count() == cnt) trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); - if (softirq_count() == (cnt & SOFTIRQ_MASK)) - trace_softirqs_on(_RET_IP_); + local_bh_enable_common(_RET_IP_, cnt); __preempt_count_sub(cnt); } @@ -170,11 +184,8 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt) #ifdef CONFIG_TRACE_IRQFLAGS local_irq_disable(); #endif - /* - * Are softirqs going to be turned on now: - */ - if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) - trace_softirqs_on(ip); + local_bh_enable_common(ip, cnt); + /* * Keep preemption disabled until we are done with * softirq processing: -- 2.21.0
