From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 5/5] proc: deduplicate /proc/*/cmdline implementation
Date: Wed, 21 Feb 2018 22:33:35 +0300 [thread overview]
Message-ID: <20180221193335.GB28678@avx2> (raw)
In-Reply-To: <20180221193009.GA28678@avx2>
Code can be sonsolidated if a dummy region of 0 length is used in normal
case of \0-separated command line:
1) [arg_start, arg_end) + [dummy len=0]
2) [arg_start, arg_end) + [env_start, env_end)
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 53 ++++++++++++++++++++---------------------------------
1 file changed, 20 insertions(+), 33 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -239,9 +239,12 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
char *page;
unsigned long count = _count;
unsigned long arg_start, arg_end, env_start, env_end;
- unsigned long len1, len2, len;
- unsigned long p;
+ unsigned long len1, len2;
char __user *buf0 = buf;
+ struct {
+ unsigned long p;
+ unsigned long len;
+ } cmdline[2];
char c;
int rv;
@@ -283,43 +286,21 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
if (access_remote_vm(mm, arg_end - 1, &c, 1, 0) != 1)
goto end;
+ cmdline[0].p = arg_start;
+ cmdline[0].len = len1;
if (c == '\0') {
/* Command line (set of strings) occupies whole ARGV. */
- if (len1 <= *pos)
- goto end;
-
- p = arg_start + *pos;
- len = len1 - *pos;
- while (count > 0 && len > 0) {
- unsigned int nr_read;
-
- nr_read = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, nr_read, 0);
- if (nr_read == 0)
- goto end;
-
- if (copy_to_user(buf, page, nr_read)) {
- rv = -EFAULT;
- goto out_free_page;
- }
-
- p += nr_read;
- len -= nr_read;
- buf += nr_read;
- count -= nr_read;
- }
+ cmdline[1].len = 0;
} else {
/*
* Command line (1 string) occupies ARGV and
* extends into ENVP.
*/
- struct {
- unsigned long p;
- unsigned long len;
- } cmdline[2] = {
- { .p = arg_start, .len = len1 },
- { .p = env_start, .len = len2 },
- };
+ cmdline[1].p = env_start;
+ cmdline[1].len = len2;
+ }
+
+ {
loff_t pos1 = *pos;
unsigned int i;
@@ -329,6 +310,9 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
i++;
}
while (i < 2) {
+ unsigned long p;
+ unsigned long len;
+
p = cmdline[i].p + pos1;
len = cmdline[i].len - pos1;
while (count > 0 && len > 0) {
@@ -343,7 +327,10 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
* Command line can be shorter than whole ARGV
* even if last "marker" byte says it is not.
*/
- nr_write = strnlen(page, nr_read);
+ if (c == '\0')
+ nr_write = nr_read;
+ else
+ nr_write = strnlen(page, nr_read);
if (copy_to_user(buf, page, nr_write)) {
rv = -EFAULT;
next prev parent reply other threads:[~2018-02-21 19:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-21 19:23 [PATCH 1/5] proc: make /proc/*/cmdline go through LSM Alexey Dobriyan
2018-02-21 19:26 ` [PATCH 2/5] proc: more "unsigned int" in /proc/*/cmdline Alexey Dobriyan
2018-02-21 19:27 ` [PATCH 3/5] proc: somewhat simpler code for /proc/*/cmdline Alexey Dobriyan
2018-02-21 19:30 ` [PATCH 4/5] proc: simpler iterations " Alexey Dobriyan
2018-02-21 19:33 ` Alexey Dobriyan [this message]
2018-04-20 0:15 ` Andrew Morton
2018-04-20 19:46 ` Alexey Dobriyan
2018-02-21 19:28 ` [PATCH 1/5] proc: make /proc/*/cmdline go through LSM Andy Shevchenko
2018-02-21 19:39 ` Alexey Dobriyan
2018-02-21 20:06 ` Andrew Morton
2018-02-23 19:43 ` [PATCH v2 " Alexey Dobriyan
2018-04-20 0:02 ` [PATCH " Andrew Morton
2018-04-20 19:25 ` Alexey Dobriyan
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