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@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index bb1c1625b158..8ae109429a88 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -286,9 +286,9 @@ int proc_readdir_de(struct file *file, struct dir_context *ctx,
         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, struct dir_context *ctx,
                         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;