Our system explicitly sets core_pattern to force a relatively small
limit on the number of different core dump names.
Unfortunately, the kernel unconditionally appends .<tid> for
multithreaded processes.
The attached patch introduces "%T" to the core_pattern language, which
expands to ".<tid>" for multithreaded processes. It then changes the
default core_pattern to "core%T" replicating the current default
behavior.
Signed-off-by: La Monte H.P. Yarroll <piggy@laurelnetworks.com> 74-256740
diff -Naur linux-2.6.26.3/Documentation/sysctl/kernel.txt linux-2.6.26.3-new/Documentation/sysctl/kernel.txt
--- linux-2.6.26.3/Documentation/sysctl/kernel.txt 2008-08-20 14:11:37.000000000 -0400
+++ linux-2.6.26.3-new/Documentation/sysctl/kernel.txt 2008-08-28 13:27:50.239325000 -0400
@@ -88,7 +88,7 @@
core_pattern:
core_pattern is used to specify a core dumpfile pattern name.
-. max length 128 characters; default value is "core"
+. max length 128 characters; default value is "core%T"
. core_pattern is used as a pattern template for the output filename;
certain string patterns (beginning with '%') are substituted with
their actual values.
@@ -104,6 +104,7 @@
%g gid
%s signal number
%t UNIX time of dump
+ %T .tgid or nothing if process is not threaded
%h hostname
%e executable filename
%<OTHER> both are dropped
diff -Naur linux-2.6.26.3/fs/exec.c linux-2.6.26.3-new/fs/exec.c
--- linux-2.6.26.3/fs/exec.c 2008-08-20 14:11:37.000000000 -0400
+++ linux-2.6.26.3-new/fs/exec.c 2008-08-28 13:46:57.919768000 -0400
@@ -66,7 +66,7 @@
#endif
int core_uses_pid;
-char core_pattern[CORENAME_MAX_SIZE] = "core";
+char core_pattern[CORENAME_MAX_SIZE] = "core%T";
int suid_dumpable = 0;
/* The maximal length of core_pattern is also specified in sysctl.c */
@@ -1415,7 +1415,7 @@
case 'p':
pid_in_pattern = 1;
rc = snprintf(out_ptr, out_end - out_ptr,
- "%d", task_tgid_vnr(current));
+ "%d", task_pid_vnr(current));
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
@@ -1455,6 +1455,17 @@
out_ptr += rc;
break;
}
+ /* Conditional tgid */
+ case 'T': {
+ if (atomic_read(¤t->mm->mm_users) != 1) {
+ rc = snprintf(out_ptr, out_end - out_ptr,
+ ".%d", task_tgid_vnr(current));
+ if (rc > out_end - out_ptr)
+ goto out;
+ out_ptr += rc;
+ }
+ break;
+ }
/* hostname */
case 'h':
down_read(&uts_sem);
@@ -1492,10 +1503,9 @@
* If core_pattern does not include a %p (as is the default)
* 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(¤t->mm->mm_users) != 1)) {
+ if (!ispipe && !pid_in_pattern && core_uses_pid) {
rc = snprintf(out_ptr, out_end - out_ptr,
- ".%d", task_tgid_vnr(current));
+ ".%d", current->pid);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
--
