After I've checked ~3/4 of spin_lock_irqsave callers and found something
like 20 deviations from unsigned long, some preventive measures should be
set up, I became sure.
So far I have 2 working (unfinished) things:
a) sparse checking
typedef unsigned long __bitwise__ lock_flags_t;
plus annotations in core and arch headers plus
s/unsigned long/lock_flags_t/
+: comprehensive checking
-: not so many folks do sparse runs, so bugs will probably
stay unnoticed longer :-(
b) compiler checking: BUILD_BUG_ON + typecheck()
needs local_irq_save() protection + it's removal from FRV.
+: in best case -- compile error, in average case: warning.
-: tiny wrappers around spin_lock_irqsave in drivers are
likely to hide offenders.
What folks want to see in tree?
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -183,13 +183,43 @@ #define write_lock(lock) _write_lock(lo
#define read_lock(lock) _read_lock(lock)
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-#define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
-#define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
-#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
+#define spin_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ flags = _spin_lock_irqsave(lock); \
+ } while (0)
+#define read_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ flags = _read_lock_irqsave(lock); \
+ } while (0)
+#define write_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ flags = _write_lock_irqsave(lock); \
+ } while (0)
#else
-#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
-#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
-#define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
+#define spin_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _spin_lock_irqsave(lock, flags); \
+ } while (0)
+#define read_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _read_lock_irqsave(lock, flags); \
+ } while (0)
+#define write_lock_irqsave(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _write_lock_irqsave(lock, flags); \
+ } while (0)
#endif
#define spin_lock_irq(lock) _spin_lock_irq(lock)
@@ -224,16 +254,28 @@ # define write_unlock_irq(lock) \
do { __raw_write_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
#endif
-#define spin_unlock_irqrestore(lock, flags) \
- _spin_unlock_irqrestore(lock, flags)
+#define spin_unlock_irqrestore(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _spin_unlock_irqrestore(lock, flags); \
+ } while (0)
#define spin_unlock_bh(lock) _spin_unlock_bh(lock)
-#define read_unlock_irqrestore(lock, flags) \
- _read_unlock_irqrestore(lock, flags)
+#define read_unlock_irqrestore(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _read_unlock_irqrestore(lock, flags); \
+ } while (0)
#define read_unlock_bh(lock) _read_unlock_bh(lock)
-#define write_unlock_irqrestore(lock, flags) \
- _write_unlock_irqrestore(lock, flags)
+#define write_unlock_irqrestore(lock, flags) \
+ do { \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
+ _write_unlock_irqrestore(lock, flags); \
+ } while (0)
#define write_unlock_bh(lock) _write_unlock_bh(lock)
#define spin_trylock_bh(lock) __cond_lock(lock, _spin_trylock_bh(lock))
@@ -247,6 +289,8 @@ ({ \
#define spin_trylock_irqsave(lock, flags) \
({ \
+ BUILD_BUG_ON(sizeof(unsigned long) != sizeof(flags)); \
+ typecheck(unsigned long, flags); \
local_irq_save(flags); \
spin_trylock(lock) ? \
1 : ({ local_irq_restore(flags); 0; }); \
-
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