mmap locking API: convert nested write lock sites

Add API for nested write locks and convert the few call sites doing that.

Michel Lespinasse committed 6 years ago

Commit aaa2cc51 parent 89154dd3 files · +8 −2Browse files

Unified · Split

3 files

arch/um/include/asm/mmu_context.h +2 −1
include/linux/mmap_lock.h +5 −0
kernel/fork.c +1 −1

arch/um/include/asm/mmu_context.h+2−1

@@ -8,6 +8,7 @@ · 7 unmodified lines
8	8
9	9	#include <linux/sched.h>
10	10	#include <linux/mm_types.h>
	11	+#include <linux/mmap_lock.h>
11	12
12	13	#include <asm/mmu.h>
13	14
@@ -47,7 +48,7 @@ static inline void activate_mm(struct mm_struct old, struct mm_struct new) · 33 unmodified lines
47	48	* when the new ->mm is used for the first time.
48	49	*/
49	50	__switch_mm(&new->context.id);
50		− down_write_nested(&new->mmap_sem, 1);
	51	+ mmap_write_lock_nested(new, SINGLE_DEPTH_NESTING);
51	52	uml_setup_stubs(new);
52	53	mmap_write_unlock(new);
53	54	}

include/linux/mmap_lock.h+5−0

@@ -11,6 +11,11 @@ static inline void mmap_write_lock(struct mm_struct *mm) · 10 unmodified lines
11	11	down_write(&mm->mmap_sem);
12	12	}
13	13
	14	+static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
	15	+{
	16	+ down_write_nested(&mm->mmap_sem, subclass);
	17	+}
	18	+
14	19	static inline int mmap_write_lock_killable(struct mm_struct *mm)
15	20	{
16	21	return down_write_killable(&mm->mmap_sem);

kernel/fork.c+1−1

@@ -501,7 +501,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, · 500 unmodified lines
501	501	/*
502	502	* Not linked in yet - no deadlock potential:
503	503	*/
504		− down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
	504	+ mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
505	505
506	506	/* No ordering required: file already has been exposed. */
507	507	RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));