The patch titled
Subject: proc: deduplicate /proc/*/cmdline implementation
has been added to the -mm tree. Its filename is
proc-deduplicate-proc-cmdline-implementation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-deduplicate-proc-cmdline-implementation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-deduplicate-proc-cmdline-implementation.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: deduplicate /proc/*/cmdline implementation
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)
Link: http://lkml.kernel.org/r/20180221193335.GB28678@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 53 +++++++++++++++++------------------------------
1 file changed, 20 insertions(+), 33 deletions(-)
diff -puN fs/proc/base.c~proc-deduplicate-proc-cmdline-implementation fs/proc/base.c
--- a/fs/proc/base.c~proc-deduplicate-proc-cmdline-implementation
+++ a/fs/proc/base.c
@@ -236,9 +236,12 @@ static ssize_t proc_pid_cmdline_read(str
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;
@@ -280,43 +283,21 @@ static ssize_t proc_pid_cmdline_read(str
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;
@@ -326,6 +307,9 @@ static ssize_t proc_pid_cmdline_read(str
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) {
@@ -340,7 +324,10 @@ static ssize_t proc_pid_cmdline_read(str
* 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;
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
proc-revalidate-kernel-thread-inodes-to-root-root.patch
proc-fix-proc-loadavg-regression.patch
proc-make-proc-cmdline-go-through-lsm.patch
proc-more-unsigned-int-in-proc-cmdline.patch
proc-somewhat-simpler-code-for-proc-cmdline.patch
proc-simpler-iterations-for-proc-cmdline.patch
proc-deduplicate-proc-cmdline-implementation.patch
coredump-fix-spam-with-zero-vma-process.patch
seq_file-delete-small-value-optimization.patch
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