Messages in this thread Patch in this message | | | Date | Sat, 7 Oct 2006 04:23:15 +0400 | From | Alexey Dobriyan <> | Subject | lock_flags_t vs typecheck(unsigned long, flags) |
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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; }); \ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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