[PATCH] Enforce "unsigned long flags;" when spinlocking

Make it break or warn if you pass to spin_lock_irqsave() and friends
something different from "unsigned long flags;".  Suprisingly large amount
of these was caught by recent commit
c53421b18f205c5f97c604ae55c6a921f034b0f6 and others.

Idea is largely from FRV typechecking. Suggestions from Andrew Morton.
All stupid typos in first version fixed.

Passes allmodconfig on i386, x86_64, alpha, arm as well as my usual config.

Note #1: checking with sparse is still needed, because a driver can save
	 and pass around flags or something. So far patch is very intrusive.
Note #2: techically, we should break only if
		sizeof(flags) < sizeof(unsigned long),
	 however, the more pain for getting suspicious code into kernel,
	 the better.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 44 insertions, 9 deletions

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index b800d2d68b32..54ad37089c49 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -52,6 +52,7 @@
 #include <linux/thread_info.h>
 #include <linux/kernel.h>
 #include <linux/stringify.h>
+#include <linux/irqflags.h>
 
 #include <asm/system.h>
 
@@ -183,13 +184,37 @@ do {								\
 #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_CHECK_IRQ_FLAGS(flags);           \
+                flags = _spin_lock_irqsave(lock);       \
+        } while (0)
+#define read_lock_irqsave(lock, flags)                  \
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(flags);           \
+                flags = _read_lock_irqsave(lock);       \
+        } while (0)
+#define write_lock_irqsave(lock, flags)                 \
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(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_CHECK_IRQ_FLAGS(flags);           \
+                _spin_lock_irqsave(lock, flags);        \
+        } while (0)
+#define read_lock_irqsave(lock, flags)                  \
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(flags);           \
+                _read_lock_irqsave(lock, flags);        \
+        } while (0)
+#define write_lock_irqsave(lock, flags)                 \
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(flags);           \
+                _write_lock_irqsave(lock, flags);       \
+        } while (0)
 #endif
 
 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
@@ -225,15 +250,24 @@ do {								\
 #endif
 
 #define spin_unlock_irqrestore(lock, flags) \
-                                        _spin_unlock_irqrestore(lock, flags)
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(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)
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(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)
+        do {                                            \
+                BUILD_CHECK_IRQ_FLAGS(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 +281,7 @@ do {								\
 
 #define spin_trylock_irqsave(lock, flags) \
 ({ \
+        BUILD_CHECK_IRQ_FLAGS(flags); \
         local_irq_save(flags); \
         spin_trylock(lock) ? \
         1 : ({ local_irq_restore(flags); 0; }); \