proc: more "unsigned int" in /proc/*/cmdline

access_remote_vm() doesn't return negative errors, it returns number of
bytes read/written (0 if error occurs).  This allows to delete some
comparisons which never trigger.

Reuse "nr_read" variable while I'm at it.

Link: http://lkml.kernel.org/r/20180221192605.GB28548@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index ef3f7df..159abd0 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -261,9 +261,10 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
         * Inherently racy -- command line shares address space
         * with code and data.
         */
-       rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_ANON);
-       if (rv <= 0)
+       if (access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_ANON) != 1) {
+               rv = 0;
                goto out_free_page;
+       }
 
        rv = 0;
 
@@ -275,14 +276,11 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
                p = arg_start + *pos;
                len = len1 - *pos;
                while (count > 0 && len > 0) {
-                       unsigned int _count;
-                       int nr_read;
-
-                       _count = min3(count, len, PAGE_SIZE);
-                       nr_read = access_remote_vm(mm, p, page, _count, FOLL_ANON);
-                       if (nr_read < 0)
-                               rv = nr_read;
-                       if (nr_read <= 0)
+                       unsigned int nr_read;
+
+                       nr_read = min3(count, len, PAGE_SIZE);
+                       nr_read = access_remote_vm(mm, p, page, nr_read, FOLL_ANON);
+                       if (nr_read == 0)
                                goto out_free_page;
 
                        if (copy_to_user(buf, page, nr_read)) {
@@ -320,15 +318,12 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
                        p = cmdline[i].p + pos1;
                        len = cmdline[i].len - pos1;
                        while (count > 0 && len > 0) {
-                               unsigned int _count, l;
-                               int nr_read;
+                               unsigned int nr_read, l;
                                bool final;
 
-                               _count = min3(count, len, PAGE_SIZE);
-                               nr_read = access_remote_vm(mm, p, page, _count, FOLL_ANON);
-                               if (nr_read < 0)
-                                       rv = nr_read;
-                               if (nr_read <= 0)
+                               nr_read = min3(count, len, PAGE_SIZE);
+                               nr_read = access_remote_vm(mm, p, page, nr_read, FOLL_ANON);
+                               if (nr_read == 0)
                                        goto out_free_page;
 
                                /*