[PATCH] coredump: format_corename: fix the "core_uses_pid" logic

From: Oleg Nesterov
Date: Sun Jul 20 2008 - 12:12:32 EST


I don't understand why the multi-thread coredump implies the core_uses_pid
behaviour, but we shouldn't use mm->mm_users for that. This counter can be
incremented by get_task_mm(). Use the valued returned by coredump_wait()
instead.

Also, remove the "const char *pattern" argument, format_corename() can use
core_pattern directly.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

--- 26-rc2/fs/exec.c~FORMAT_CORENAME 2008-07-20 17:06:07.000000000 +0400
+++ 26-rc2/fs/exec.c 2008-07-20 17:31:40.000000000 +0400
@@ -1373,17 +1373,14 @@ EXPORT_SYMBOL(set_binfmt);
* name into corename, which must have space for at least
* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
*/
-static int format_corename(char *corename, const char *pattern, long signr)
+static int format_corename(char *corename, int nr_threads, long signr)
{
- const char *pat_ptr = pattern;
+ const char *pat_ptr = core_pattern;
+ int ispipe = (*pat_ptr == '|');
char *out_ptr = corename;
char *const out_end = corename + CORENAME_MAX_SIZE;
int rc;
int pid_in_pattern = 0;
- int ispipe = 0;
-
- if (*pattern == '|')
- ispipe = 1;

/* Repeat as long as we have more pattern to process and more output
space */
@@ -1484,7 +1481,7 @@ static int format_corename(char *corenam
* and core_uses_pid is set, then .%pid will be appended to
* the filename. Do not do this for piped commands. */
if (!ispipe && !pid_in_pattern
- && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
+ && (core_uses_pid || nr_threads)) {
rc = snprintf(out_ptr, out_end - out_ptr,
".%d", task_tgid_vnr(current));
if (rc > out_end - out_ptr)
@@ -1748,7 +1745,7 @@ int do_coredump(long signr, int exit_cod
* uses lock_kernel()
*/
lock_kernel();
- ispipe = format_corename(corename, core_pattern, signr);
+ ispipe = format_corename(corename, retval, signr);
unlock_kernel();
/*
* Don't bother to check the RLIMIT_CORE value if core_pattern points

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