locking/refcounts: Change WARN() to WARN_ONCE()

Linus noticed that the new refcount.h APIs used WARN(), which would turn
into a dmesg DoS if it triggers frequently on some buggy driver.

So make sure we only warn once. These warnings are never supposed to happen,
so it's typically not a problem to lose subsequent warnings.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/CA+55aFzbYUTZ=oqZ2YgDjY0C2_n6ODhTfqj6V+m5xWmDxsuB0w@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/lib/refcount.c b/lib/refcount.c
index 1d33366189d10c88bf10616e6a9b25c64c4bf570..aa09ad3c30b0dc37a920c46f0da711f366d29423 100644 (file)
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -58,7 +58,7 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r)
                val = old;
        }
 
-       WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
+       WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
 
        return true;
 }
@@ -66,7 +66,7 @@ EXPORT_SYMBOL_GPL(refcount_add_not_zero);
 
 void refcount_add(unsigned int i, refcount_t *r)
 {
-       WARN(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n");
+       WARN_ONCE(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n");
 }
 EXPORT_SYMBOL_GPL(refcount_add);
 
@@ -97,7 +97,7 @@ bool refcount_inc_not_zero(refcount_t *r)
                val = old;
        }
 
-       WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
+       WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
 
        return true;
 }
@@ -111,7 +111,7 @@ EXPORT_SYMBOL_GPL(refcount_inc_not_zero);
  */
 void refcount_inc(refcount_t *r)
 {
-       WARN(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n");
+       WARN_ONCE(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n");
 }
 EXPORT_SYMBOL_GPL(refcount_inc);
 
@@ -125,7 +125,7 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r)
 
                new = val - i;
                if (new > val) {
-                       WARN(new > val, "refcount_t: underflow; use-after-free.\n");
+                       WARN_ONCE(new > val, "refcount_t: underflow; use-after-free.\n");
                        return false;
                }
 
@@ -164,7 +164,7 @@ EXPORT_SYMBOL_GPL(refcount_dec_and_test);
 
 void refcount_dec(refcount_t *r)
 {
-       WARN(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n");
+       WARN_ONCE(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n");
 }
 EXPORT_SYMBOL_GPL(refcount_dec);
 
@@ -204,7 +204,7 @@ bool refcount_dec_not_one(refcount_t *r)
 
                new = val - 1;
                if (new > val) {
-                       WARN(new > val, "refcount_t: underflow; use-after-free.\n");
+                       WARN_ONCE(new > val, "refcount_t: underflow; use-after-free.\n");
                        return true;
                }