mwifiex: Fix possible buffer overflows in mwifiex_ret_wmm_get_status()

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / lib / dump_stack.c

diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index 6745c62..72de644 100644 (file)
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -25,6 +25,7 @@ static atomic_t dump_lock = ATOMIC_INIT(-1);
 
 asmlinkage __visible void dump_stack(void)
 {
+       unsigned long flags;
        int was_locked;
        int old;
        int cpu;
@@ -33,9 +34,8 @@ asmlinkage __visible void dump_stack(void)
         * Permit this cpu to perform nested stack dumps while serialising
         * against other CPUs
         */
-       preempt_disable();
-
 retry:
+       local_irq_save(flags);
        cpu = smp_processor_id();
        old = atomic_cmpxchg(&dump_lock, -1, cpu);
        if (old == -1) {
@@ -43,7 +43,13 @@ retry:
        } else if (old == cpu) {
                was_locked = 1;
        } else {
-               cpu_relax();
+               local_irq_restore(flags);
+               /*
+                * Wait for the lock to release before jumping to
+                * atomic_cmpxchg() in order to mitigate the thundering herd
+                * problem.
+                */
+               do { cpu_relax(); } while (atomic_read(&dump_lock) != -1);
                goto retry;
        }
 
@@ -52,7 +58,7 @@ retry:
        if (!was_locked)
                atomic_set(&dump_lock, -1);
 
-       preempt_enable();
+       local_irq_restore(flags);
 }
 #else
 asmlinkage __visible void dump_stack(void)