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Commit b3c395ef authored May 11, 2015 by David Hildenbrand Committed by Ingo Molnar May 19, 2015

mm/uaccess, mm/fault: Clarify that uaccess may only sleep if pagefaults are enabled



In general, non-atomic variants of user access functions must not sleep
if pagefaults are disabled.

Let's update all relevant comments in uaccess code. This also reflects
the might_sleep() checks in might_fault().

Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-4-git-send-email-dahi@linux.vnet.ibm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 9ec23531

arch/avr32/include/asm/uaccess.h

+8 −4

Original line number	Original line	Diff line number	Diff line
	@@ -97,7 +97,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -116,7 +117,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -136,7 +138,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -158,7 +161,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger

arch/hexagon/include/asm/uaccess.h

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -36,7 +36,8 @@
	* @addr: User space pointer to start of block to check		* @addr: User space pointer to start of block to check
	* @size: Size of block to check		* @size: Size of block to check
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Checks if a pointer to a block of memory in user space is valid.		* Checks if a pointer to a block of memory in user space is valid.
	*		*

arch/m32r/include/asm/uaccess.h

+20 −10

Original line number	Original line	Diff line number	Diff line
	@@ -91,7 +91,8 @@ static inline void set_fs(mm_segment_t s)
	* @addr: User space pointer to start of block to check		* @addr: User space pointer to start of block to check
	* @size: Size of block to check		* @size: Size of block to check
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Checks if a pointer to a block of memory in user space is valid.		* Checks if a pointer to a block of memory in user space is valid.
	*		*
	@@ -155,7 +156,8 @@ extern int fixup_exception(struct pt_regs *regs);
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -175,7 +177,8 @@ extern int fixup_exception(struct pt_regs *regs);
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -194,7 +197,8 @@ extern int fixup_exception(struct pt_regs *regs);
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -274,7 +278,8 @@ do { \
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -568,7 +573,8 @@ unsigned long __generic_copy_from_user(void , const void __user , unsigned lon
	* @from: Source address, in kernel space.		* @from: Source address, in kernel space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from kernel space to user space. Caller must check		* Copy data from kernel space to user space. Caller must check
	* the specified block with access_ok() before calling this function.		* the specified block with access_ok() before calling this function.
	@@ -588,7 +594,8 @@ unsigned long __generic_copy_from_user(void , const void __user , unsigned lon
	* @from: Source address, in kernel space.		* @from: Source address, in kernel space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from kernel space to user space.		* Copy data from kernel space to user space.
	*		*
	@@ -606,7 +613,8 @@ unsigned long __generic_copy_from_user(void , const void __user , unsigned lon
	* @from: Source address, in user space.		* @from: Source address, in user space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from user space to kernel space. Caller must check		* Copy data from user space to kernel space. Caller must check
	* the specified block with access_ok() before calling this function.		* the specified block with access_ok() before calling this function.
	@@ -626,7 +634,8 @@ unsigned long __generic_copy_from_user(void , const void __user , unsigned lon
	* @from: Source address, in user space.		* @from: Source address, in user space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from user space to kernel space.		* Copy data from user space to kernel space.
	*		*
	@@ -677,7 +686,8 @@ unsigned long clear_user(void __user *mem, unsigned long len);
	* strlen_user: - Get the size of a string in user space.		* strlen_user: - Get the size of a string in user space.
	* @str: The string to measure.		* @str: The string to measure.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Get the size of a NUL-terminated string in user space.		* Get the size of a NUL-terminated string in user space.
	*		*

arch/microblaze/include/asm/uaccess.h

+4 −2

Original line number	Original line	Diff line number	Diff line
	@@ -178,7 +178,8 @@ extern long __user_bad(void);
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -290,7 +291,8 @@ extern long __user_bad(void);
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger

arch/mips/include/asm/uaccess.h

+30 −15

Original line number	Original line	Diff line number	Diff line
	@@ -103,7 +103,8 @@ extern u64 __ua_limit;
	* @addr: User space pointer to start of block to check		* @addr: User space pointer to start of block to check
	* @size: Size of block to check		* @size: Size of block to check
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Checks if a pointer to a block of memory in user space is valid.		* Checks if a pointer to a block of memory in user space is valid.
	*		*
	@@ -138,7 +139,8 @@ extern u64 __ua_limit;
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -157,7 +159,8 @@ extern u64 __ua_limit;
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -177,7 +180,8 @@ extern u64 __ua_limit;
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -199,7 +203,8 @@ extern u64 __ua_limit;
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -498,7 +503,8 @@ extern void __put_user_unknown(void);
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -517,7 +523,8 @@ extern void __put_user_unknown(void);
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -537,7 +544,8 @@ extern void __put_user_unknown(void);
	* @x: Value to copy to user space.		* @x: Value to copy to user space.
	* @ptr: Destination address, in user space.		* @ptr: Destination address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple value from kernel space to user		* This macro copies a single simple value from kernel space to user
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -559,7 +567,8 @@ extern void __put_user_unknown(void);
	* @x: Variable to store result.		* @x: Variable to store result.
	* @ptr: Source address, in user space.		* @ptr: Source address, in user space.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* This macro copies a single simple variable from user space to kernel		* This macro copies a single simple variable from user space to kernel
	* space. It supports simple types like char and int, but not larger		* space. It supports simple types like char and int, but not larger
	@@ -815,7 +824,8 @@ extern size_t __copy_user(void __to, const void __from, size_t __n);
	* @from: Source address, in kernel space.		* @from: Source address, in kernel space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from kernel space to user space. Caller must check		* Copy data from kernel space to user space. Caller must check
	* the specified block with access_ok() before calling this function.		* the specified block with access_ok() before calling this function.
	@@ -888,7 +898,8 @@ extern size_t __copy_user_inatomic(void __to, const void __from, size_t __n);
	* @from: Source address, in kernel space.		* @from: Source address, in kernel space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from kernel space to user space.		* Copy data from kernel space to user space.
	*		*
	@@ -1075,7 +1086,8 @@ extern size_t __copy_in_user_eva(void __to, const void __from, size_t __n);
	* @from: Source address, in user space.		* @from: Source address, in user space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from user space to kernel space. Caller must check		* Copy data from user space to kernel space. Caller must check
	* the specified block with access_ok() before calling this function.		* the specified block with access_ok() before calling this function.
	@@ -1107,7 +1119,8 @@ extern size_t __copy_in_user_eva(void __to, const void __from, size_t __n);
	* @from: Source address, in user space.		* @from: Source address, in user space.
	* @n: Number of bytes to copy.		* @n: Number of bytes to copy.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Copy data from user space to kernel space.		* Copy data from user space to kernel space.
	*		*
	@@ -1329,7 +1342,8 @@ strncpy_from_user(char __to, const char __user __from, long __len)
	* strlen_user: - Get the size of a string in user space.		* strlen_user: - Get the size of a string in user space.
	* @str: The string to measure.		* @str: The string to measure.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Get the size of a NUL-terminated string in user space.		* Get the size of a NUL-terminated string in user space.
	*		*
	@@ -1398,7 +1412,8 @@ static inline long __strnlen_user(const char __user *s, long n)
	* strnlen_user: - Get the size of a string in user space.		* strnlen_user: - Get the size of a string in user space.
	* @str: The string to measure.		* @str: The string to measure.
	*		*
	* Context: User context only. This function may sleep.		* Context: User context only. This function may sleep if pagefaults are
			* enabled.
	*		*
	* Get the size of a NUL-terminated string in user space.		* Get the size of a NUL-terminated string in user space.
	*		*