From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: smaller readlock section in readdir("/proc")
Readdir context is thread local, so ->pos is thread local,
move it out of readlock.
Link: http://lkml.kernel.org/r/20180627195339.GD18113@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/generic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/proc/generic.c~proc-smaller-readlock-section-in-readdir-proc
+++ a/fs/proc/generic.c
@@ -286,9 +286,9 @@ int proc_readdir_de(struct file *file, s
if (!dir_emit_dots(file, ctx))
return 0;
+ i = ctx->pos - 2;
read_lock(&proc_subdir_lock);
de = pde_subdir_first(de);
- i = ctx->pos - 2;
for (;;) {
if (!de) {
read_unlock(&proc_subdir_lock);
@@ -309,8 +309,8 @@ int proc_readdir_de(struct file *file, s
pde_put(de);
return 0;
}
- read_lock(&proc_subdir_lock);
ctx->pos++;
+ read_lock(&proc_subdir_lock);
next = pde_subdir_next(de);
pde_put(de);
de = next;
_
