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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/
This commit is contained in:
Linus Torvalds 2013-07-02 16:19:24 -07:00
parent 2d722f6d56 662bbcb274
commit e13053f506
11 changed files with 39 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/include/asm/uaccess.h
View File

@ -166,7 +166,7 @@ do { \
#define get_user(x, ptr) \
({ \
might_sleep(); \
might_fault(); \
access_ok(VERIFY_READ, (ptr), sizeof(*(ptr))) ? \
__get_user((x), (ptr)) : \
((x) = 0, -EFAULT); \
@ -227,7 +227,7 @@ do { \
#define put_user(x, ptr) \
({ \
might_sleep(); \
might_fault(); \
access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
__put_user((x), (ptr)) : \
-EFAULT; \

4
arch/frv/include/asm/uaccess.h
View File

@ -280,14 +280,14 @@ extern long __memcpy_user(void *dst, const void *src, unsigned long count);
static inline unsigned long __must_check
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
might_sleep();
might_fault();
return __copy_to_user_inatomic(to, from, n);
}
static inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
might_sleep();
might_fault();
return __copy_from_user_inatomic(to, from, n);
}

12
arch/m32r/include/asm/uaccess.h
View File

@ -216,7 +216,7 @@ extern int fixup_exception(struct pt_regs *regs);
({ \
long __gu_err = 0; \
unsigned long __gu_val; \
might_sleep(); \
might_fault(); \
__get_user_size(__gu_val,(ptr),(size),__gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
@ -227,7 +227,7 @@ extern int fixup_exception(struct pt_regs *regs);
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
might_sleep(); \
might_fault(); \
if (access_ok(VERIFY_READ,__gu_addr,size)) \
__get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
@ -295,7 +295,7 @@ do { \
#define __put_user_nocheck(x,ptr,size) \
({ \
long __pu_err; \
might_sleep(); \
might_fault(); \
__put_user_size((x),(ptr),(size),__pu_err); \
__pu_err; \
})
@ -305,7 +305,7 @@ do { \
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
might_sleep(); \
might_fault(); \
if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
__put_user_size((x),__pu_addr,(size),__pu_err); \
__pu_err; \
@ -597,7 +597,7 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
*/
#define copy_to_user(to,from,n) \
({ \
might_sleep(); \
might_fault(); \
__generic_copy_to_user((to),(from),(n)); \
})
@ -638,7 +638,7 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
*/
#define copy_from_user(to,from,n) \
({ \
might_sleep(); \
might_fault(); \
__generic_copy_from_user((to),(from),(n)); \
})

6
arch/microblaze/include/asm/uaccess.h
View File

@ -145,7 +145,7 @@ static inline unsigned long __must_check __clear_user(void __user *to,
static inline unsigned long __must_check clear_user(void __user *to,
unsigned long n)
{
might_sleep();
might_fault();
if (unlikely(!access_ok(VERIFY_WRITE, to, n)))
return n;
@ -371,7 +371,7 @@ extern long __user_bad(void);
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);
return n;
@ -385,7 +385,7 @@ 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);
return n;

4
arch/mn10300/include/asm/uaccess.h
View File

@ -471,13 +471,13 @@ extern unsigned long __generic_copy_from_user(void *, const void __user *,
#define __copy_to_user(to, from, n) \
({ \
might_sleep(); \
might_fault(); \
__copy_to_user_inatomic((to), (from), (n)); \
})
#define __copy_from_user(to, from, n) \
({ \
might_sleep(); \
might_fault(); \
__copy_from_user_inatomic((to), (from), (n)); \
})

16
arch/powerpc/include/asm/uaccess.h
View File

@ -178,7 +178,7 @@ do { \
long __pu_err; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
if (!is_kernel_addr((unsigned long)__pu_addr)) \
might_sleep(); \
might_fault(); \
__chk_user_ptr(ptr); \
__put_user_size((x), __pu_addr, (size), __pu_err); \
__pu_err; \
@ -188,7 +188,7 @@ do { \
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
might_sleep(); \
might_fault(); \
if (access_ok(VERIFY_WRITE, __pu_addr, size)) \
__put_user_size((x), __pu_addr, (size), __pu_err); \
__pu_err; \
@ -268,7 +268,7 @@ do { \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
if (!is_kernel_addr((unsigned long)__gu_addr)) \
might_sleep(); \
might_fault(); \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
@ -282,7 +282,7 @@ do { \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
if (!is_kernel_addr((unsigned long)__gu_addr)) \
might_sleep(); \
might_fault(); \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
@ -294,7 +294,7 @@ do { \
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
might_sleep(); \
might_fault(); \
if (access_ok(VERIFY_READ, __gu_addr, (size))) \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
@ -419,14 +419,14 @@ static inline unsigned long __copy_to_user_inatomic(void __user *to,
static inline unsigned long __copy_from_user(void *to,
const void __user *from, unsigned long size)
{
might_sleep();
might_fault();
return __copy_from_user_inatomic(to, from, size);
}
static inline unsigned long __copy_to_user(void __user *to,
const void *from, unsigned long size)
{
might_sleep();
might_fault();
return __copy_to_user_inatomic(to, from, size);
}
@ -434,7 +434,7 @@ extern unsigned long __clear_user(void __user *addr, unsigned long size);
static inline unsigned long clear_user(void __user *addr, unsigned long size)
{
might_sleep();
might_fault();
if (likely(access_ok(VERIFY_WRITE, addr, size)))
return __clear_user(addr, size);
if ((unsigned long)addr < TASK_SIZE) {

2
arch/tile/include/asm/uaccess.h
View File

@ -442,7 +442,7 @@ extern unsigned long __copy_in_user_inatomic(
static inline unsigned long __must_check
__copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
might_sleep();
might_fault();
return __copy_in_user_inatomic(to, from, n);
}

2
arch/x86/include/asm/uaccess_64.h
View File

@ -235,7 +235,7 @@ extern long __copy_user_nocache(void *dst, const void __user *src,
static inline int
__copy_from_user_nocache(void *dst, const void __user *src, unsigned size)
{
might_sleep();
might_fault();
return __copy_user_nocache(dst, src, size, 1);
}

10
include/asm-generic/uaccess.h
View File

@ -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;

7
include/linux/kernel.h
View File

@ -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;

10
mm/memory.c
View File

@ -4201,7 +4201,7 @@ void print_vma_addr(char *prefix, unsigned long ip)
up_read(&mm->mmap_sem);
}
#ifdef CONFIG_PROVE_LOCKING
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
void might_fault(void)
{
/*
@ -4213,13 +4213,17 @@ void might_fault(void)
if (segment_eq(get_fs(), KERNEL_DS))
return;
might_sleep();
/*
* it would be nicer only to annotate paths which are not under
* pagefault_disable, however that requires a larger audit and
* providing helpers like get_user_atomic.
*/
if (!in_atomic() && current->mm)
if (in_atomic())
return;
__might_sleep(__FILE__, __LINE__, 0);
if (current->mm)
might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);