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127 lines
4.4 KiB
C
127 lines
4.4 KiB
C
#ifndef _LINUX_SCHED_MM_H
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#define _LINUX_SCHED_MM_H
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#define PF_MEMALLOC 0x00000800 /* Allocating memory */
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#define PF_MEMALLOC_NOFS 0x00040000 /* All allocation requests will inherit GFP_NOFS */
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/**
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* memalloc_flags_save - Add a PF_* flag to current->flags, save old value
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*
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* This allows PF_* flags to be conveniently added, irrespective of current
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* value, and then the old version restored with memalloc_flags_restore().
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*/
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static inline unsigned memalloc_flags_save(unsigned flags)
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{
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unsigned oldflags = ~current->flags & flags;
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current->flags |= flags;
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return oldflags;
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}
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static inline void memalloc_flags_restore(unsigned flags)
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{
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current->flags &= ~flags;
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}
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/**
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* memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
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*
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* This functions marks the beginning of the GFP_NOIO allocation scope.
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* All further allocations will implicitly drop __GFP_IO flag and so
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* they are safe for the IO critical section from the allocation recursion
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* point of view. Use memalloc_noio_restore to end the scope with flags
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* returned by this function.
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*
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* Context: This function is safe to be used from any context.
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* Return: The saved flags to be passed to memalloc_noio_restore.
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*/
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static inline unsigned int memalloc_noio_save(void)
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{
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return memalloc_flags_save(PF_MEMALLOC_NOIO);
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}
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/**
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* memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
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* @flags: Flags to restore.
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*
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* Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
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* Always make sure that the given flags is the return value from the
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* pairing memalloc_noio_save call.
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*/
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static inline void memalloc_noio_restore(unsigned int flags)
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{
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memalloc_flags_restore(flags);
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}
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/**
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* memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
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*
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* This functions marks the beginning of the GFP_NOFS allocation scope.
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* All further allocations will implicitly drop __GFP_FS flag and so
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* they are safe for the FS critical section from the allocation recursion
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* point of view. Use memalloc_nofs_restore to end the scope with flags
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* returned by this function.
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*
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* Context: This function is safe to be used from any context.
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* Return: The saved flags to be passed to memalloc_nofs_restore.
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*/
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static inline unsigned int memalloc_nofs_save(void)
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{
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return memalloc_flags_save(PF_MEMALLOC_NOFS);
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}
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/**
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* memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
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* @flags: Flags to restore.
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*
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* Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
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* Always make sure that the given flags is the return value from the
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* pairing memalloc_nofs_save call.
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*/
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static inline void memalloc_nofs_restore(unsigned int flags)
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{
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memalloc_flags_restore(flags);
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}
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/**
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* memalloc_noreclaim_save - Marks implicit __GFP_MEMALLOC scope.
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*
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* This function marks the beginning of the __GFP_MEMALLOC allocation scope.
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* All further allocations will implicitly add the __GFP_MEMALLOC flag, which
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* prevents entering reclaim and allows access to all memory reserves. This
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* should only be used when the caller guarantees the allocation will allow more
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* memory to be freed very shortly, i.e. it needs to allocate some memory in
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* the process of freeing memory, and cannot reclaim due to potential recursion.
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*
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* Users of this scope have to be extremely careful to not deplete the reserves
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* completely and implement a throttling mechanism which controls the
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* consumption of the reserve based on the amount of freed memory. Usage of a
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* pre-allocated pool (e.g. mempool) should be always considered before using
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* this scope.
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*
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* Individual allocations under the scope can opt out using __GFP_NOMEMALLOC
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*
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* Context: This function should not be used in an interrupt context as that one
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* does not give PF_MEMALLOC access to reserves.
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* See __gfp_pfmemalloc_flags().
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* Return: The saved flags to be passed to memalloc_noreclaim_restore.
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*/
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static inline unsigned int memalloc_noreclaim_save(void)
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{
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return memalloc_flags_save(PF_MEMALLOC);
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}
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/**
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* memalloc_noreclaim_restore - Ends the implicit __GFP_MEMALLOC scope.
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* @flags: Flags to restore.
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*
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* Ends the implicit __GFP_MEMALLOC scope started by memalloc_noreclaim_save
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* function. Always make sure that the given flags is the return value from the
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* pairing memalloc_noreclaim_save call.
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*/
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static inline void memalloc_noreclaim_restore(unsigned int flags)
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{
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memalloc_flags_restore(flags);
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}
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#endif /* _LINUX_SCHED_MM_H */
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