mirros/rockchip-kernel
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ANDROID: mm: use raw seqcount variants in vm_write_*

Browse Source 
write_seqcount_begin expects to be called from a non-preemptible
context to avoid preemption by a read section that can spin due
to an odd value. But the readers of vm_sequence never retries and
thus writers need not disable preemption. Use the non-lockdep
variant as lockdep checks are now in-built to write_seqcount_begin.

Bug: 161210518
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Change-Id: If4f0cddd7f0a79136495060d4acc1702abb46817
This commit is contained in:
Vinayak Menon
2021-01-15 19:52:40 +05:30
committed by Suren Baghdasaryan
parent 531f65ae67
commit c9201630e8
3 changed files with 18 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
include/linux/mm.h
View File

@@ -1713,22 +1713,13 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
static inline void vm_write_begin(struct vm_area_struct *vma)
{
write_seqcount_begin(&vma->vm_sequence);
}
static inline void vm_write_begin_nested(struct vm_area_struct *vma,
int subclass)
{
write_seqcount_begin_nested(&vma->vm_sequence, subclass);
}
static inline void vm_write_end(struct vm_area_struct *vma)
{
write_seqcount_end(&vma->vm_sequence);
}
static inline void vm_raw_write_begin(struct vm_area_struct *vma)
{
/*
* The reads never spins and preemption
* disablement is not required.
*/
raw_write_seqcount_begin(&vma->vm_sequence);
}
static inline void vm_raw_write_end(struct vm_area_struct *vma)
static inline void vm_write_end(struct vm_area_struct *vma)
{
raw_write_seqcount_end(&vma->vm_sequence);
}
@@ -1736,19 +1727,9 @@ static inline void vm_raw_write_end(struct vm_area_struct *vma)
static inline void vm_write_begin(struct vm_area_struct *vma)
{
}
static inline void vm_write_begin_nested(struct vm_area_struct *vma,
int subclass)
{
}
static inline void vm_write_end(struct vm_area_struct *vma)
{
}
static inline void vm_raw_write_begin(struct vm_area_struct *vma)
{
}
static inline void vm_raw_write_end(struct vm_area_struct *vma)
{
}
#endif /* CONFIG_SPECULATIVE_PAGE_FAULT */
extern void truncate_pagecache(struct inode *inode, loff_t new);