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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:19:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:19:24 -0700
commite13053f50664d3d614bbc9b8c83abdad979ac7c9 (patch)
tree07ee41cd50ba26bd7ec92255184f80aff70a2e9a /include
parent2d722f6d5671794c0de0e29e3da75006ac086718 (diff)
parent662bbcb2747c2422cf98d3d97619509379eee466 (diff)
Merge branch 'sched-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull voluntary preemption fixes from Ingo Molnar: "This tree contains a speedup which is achieved through better might_sleep()/might_fault() preemption point annotations for uaccess functions, by Michael S Tsirkin: 1. The only reason uaccess routines might sleep is if they fault. Make this explicit for all architectures. 2. A voluntary preemption point in uaccess functions means compiler can't inline them efficiently, this breaks assumptions that they are very fast and small that e.g. net code seems to make. Remove this preemption point so behaviour matches with what callers assume. 3. Accesses (e.g through socket ops) to kernel memory with KERNEL_DS like net/sunrpc does will never sleep. Remove an unconditinal might_sleep() in the might_fault() inline in kernel.h (used when PROVE_LOCKING is not set). 4. Accesses with pagefault_disable() return EFAULT but won't cause caller to sleep. Check for that and thus avoid might_sleep() when PROVE_LOCKING is set. These changes offer a nice speedup for CONFIG_PREEMPT_VOLUNTARY=y kernels, here's a network bandwidth measurement between a virtual machine and the host: before: incoming: 7122.77 Mb/s outgoing: 8480.37 Mb/s after: incoming: 8619.24 Mb/s [ +21.0% ] outgoing: 9455.42 Mb/s [ +11.5% ] I kept these changes in a separate tree, separate from scheduler changes, because it's a mixed MM and scheduler topic" * 'sched-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: mm, sched: Allow uaccess in atomic with pagefault_disable() mm, sched: Drop voluntary schedule from might_fault() x86: uaccess s/might_sleep/might_fault/ tile: uaccess s/might_sleep/might_fault/ powerpc: uaccess s/might_sleep/might_fault/ mn10300: uaccess s/might_sleep/might_fault/ microblaze: uaccess s/might_sleep/might_fault/ m32r: uaccess s/might_sleep/might_fault/ frv: uaccess s/might_sleep/might_fault/ arm64: uaccess s/might_sleep/might_fault/ asm-generic: uaccess s/might_sleep/might_fault/
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/uaccess.h10
-rw-r--r--include/linux/kernel.h7
2 files changed, 7 insertions, 10 deletions
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index c184aa8ec8c..dc1269c74a5 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -163,7 +163,7 @@ static inline __must_check long __copy_to_user(void __user *to,
#define put_user(x, ptr) \
({ \
- might_sleep(); \
+ might_fault(); \
access_ok(VERIFY_WRITE, ptr, sizeof(*ptr)) ? \
__put_user(x, ptr) : \
-EFAULT; \
@@ -225,7 +225,7 @@ extern int __put_user_bad(void) __attribute__((noreturn));
#define get_user(x, ptr) \
({ \
- might_sleep(); \
+ might_fault(); \
access_ok(VERIFY_READ, ptr, sizeof(*ptr)) ? \
__get_user(x, ptr) : \
-EFAULT; \
@@ -255,7 +255,7 @@ extern int __get_user_bad(void) __attribute__((noreturn));
static inline long copy_from_user(void *to,
const void __user * from, unsigned long n)
{
- might_sleep();
+ might_fault();
if (access_ok(VERIFY_READ, from, n))
return __copy_from_user(to, from, n);
else
@@ -265,7 +265,7 @@ static inline long copy_from_user(void *to,
static inline long copy_to_user(void __user *to,
const void *from, unsigned long n)
{
- might_sleep();
+ might_fault();
if (access_ok(VERIFY_WRITE, to, n))
return __copy_to_user(to, from, n);
else
@@ -336,7 +336,7 @@ __clear_user(void __user *to, unsigned long n)
static inline __must_check unsigned long
clear_user(void __user *to, unsigned long n)
{
- might_sleep();
+ might_fault();
if (!access_ok(VERIFY_WRITE, to, n))
return n;
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3afb969441d..7e6b97e77fb 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -193,13 +193,10 @@ extern int _cond_resched(void);
(__x < 0) ? -__x : __x; \
})
-#ifdef CONFIG_PROVE_LOCKING
+#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
void might_fault(void);
#else
-static inline void might_fault(void)
-{
- might_sleep();
-}
+static inline void might_fault(void) { }
#endif
extern struct atomic_notifier_head panic_notifier_list;