workqueue: increase max_active of keventd and kill current_is_keventd()

Define WQ_MAX_ACTIVE and create keventd with max_active set to half of
it which means that keventd now can process upto WQ_MAX_ACTIVE / 2 - 1
works concurrently.  Unless some combination can result in dependency
loop longer than max_active, deadlock won't happen and thus it's
unnecessary to check whether current_is_keventd() before trying to
schedule a work.  Kill current_is_keventd().

(Lockdep annotations are broken.  We need lock_map_acquire_read_norecurse())

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 6a1380e90f87..99dcc85193c9 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -519,7 +519,7 @@ do_boot_cpu (int sapicid, int cpu)
         /*
          * We can't use kernel_thread since we must avoid to reschedule the child.
          */
-        if (!keventd_up() || current_is_keventd())
+        if (!keventd_up())
                 c_idle.work.func(&c_idle.work);
         else {
                 schedule_work(&c_idle.work);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index c4f33b2e77d6..4d90f376e985 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -735,7 +735,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
                 goto do_rest;
         }
 
-        if (!keventd_up() || current_is_keventd())
+        if (!keventd_up())
                 c_idle.work.func(&c_idle.work);
         else {
                 schedule_work(&c_idle.work);