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Date: Mon, 10 Nov 2008 11:42:29 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>,
linux-next@...r.kernel.org, Ken Chen <kenchen@...gle.com>,
linux-kernel@...r.kernel.org, linux-api@...r.kernel.org
Subject: [PATCH v42] proc: add /proc/*/stack (was Re: linux-next: proc tree
build failure)
On Mon, Nov 10, 2008 at 08:36:23AM +0100, Ingo Molnar wrote:
>
> * Alexey Dobriyan <adobriyan@...il.com> wrote:
>
> > On Mon, Nov 10, 2008 at 04:29:41PM +1100, Stephen Rothwell wrote:
> > > Today's linux-next build (powerpc ppc64_defconfig) failed like this:
> > >
> > > fs/proc/base.c:2547: error: 'pid_stack' undeclared here (not in a function)
> > >
> > > Caused by an interaction of commits
> > > 078e9901c02d4899db5b24f708b8dfbca8935891 ("stacktrace:
> > > add /proc/<pid>/stack to dump task's stack trace") and
> > > 35f0b5fd7fab907a1119eaa614d9b24e5e225755 ("stacktrace:
> > > convert /proc/<pid>/stack to seqfiles") from the tip-core tree with commit
> > > 5d8880e3e0fb96459c652ac5e1504b90c949b3b9 ("proc: remove '##' usage") from
> > > the proc tree.
> > >
> > > The former added a new usage of INF (which the second converted to a
> > > ONE). I added the following patch to the merge of the proc tree and can
> > > carry it.
> >
> > Time to steal this /proc/*/stack from Ingo. :-)
>
> Alexey, would you like to carry them for v2.6.29? They are in a
> separate tree here, the pull coordinates are below.
>
> Please preserve the sha1's (do not rebase/cherry-pick, etc.) so that i
> can carry it too without causing confusion.
Sorry, I can't.
It's two commits, PROC_BLOCK_SIZE moving chunk is now unneeded, because
seqfiles are in use, grabbing tasklist_lock for protection from task
dissapearing is unneeded -- proc_single_show() pins task_struct, entry
is added only to tgid table.
So, here is final version:
commit 12bf5a00732a5f9512081291097d0e4a3224e8a3
Author: Ken Chen <kenchen@...gle.com>
Date: Mon Nov 10 11:26:08 2008 +0300
proc: add /proc/*/stack
/proc/*/stack adds the ability to query a task's stack trace. It is more
useful than /proc/*/wchan as it provides full stack trace instead of single
depth. Example output:
$ cat /proc/self/stack
[<c010a271>] save_stack_trace_tsk+0x17/0x35
[<c01827b4>] proc_pid_stack+0x4a/0x76
[<c018312d>] proc_single_show+0x4a/0x5e
[<c016bdec>] seq_read+0xf3/0x29f
[<c015a004>] vfs_read+0x6d/0x91
[<c015a0c1>] sys_read+0x3b/0x60
[<c0102eda>] syscall_call+0x7/0xb
[<ffffffff>] 0xffffffff
Signed-off-by: Ken Chen <kenchen@...gle.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index bcceb99..11f5b75 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -139,6 +139,7 @@ Table 1-1: Process specific entries in /proc
statm Process memory status information
status Process status in human readable form
wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
+ stack Report full stack trace, enable via CONFIG_STACKTRACE
smaps Extension based on maps, the rss size for each mapped file
..............................................................................
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6e850e9..738ea78 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -65,6 +65,7 @@
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
+#include <linux/stacktrace.h>
#include <linux/resource.h>
#include <linux/module.h>
#include <linux/mount.h>
@@ -337,6 +338,37 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer)
}
#endif /* CONFIG_KALLSYMS */
+#ifdef CONFIG_STACKTRACE
+
+#define MAX_STACK_TRACE_DEPTH 64
+
+static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
+{
+ struct stack_trace trace;
+ unsigned long *entries;
+ int i;
+
+ entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
+ if (!entries)
+ return -ENOMEM;
+
+ trace.nr_entries = 0;
+ trace.max_entries = MAX_STACK_TRACE_DEPTH;
+ trace.entries = entries;
+ trace.skip = 0;
+ save_stack_trace_tsk(task, &trace);
+
+ for (i = 0; i < trace.nr_entries; i++) {
+ seq_printf(m, "[<%p>] %pS\n",
+ (void *)entries[i], (void *)entries[i]);
+ }
+ kfree(entries);
+
+ return 0;
+}
+#endif
+
#ifdef CONFIG_SCHEDSTATS
/*
* Provides /proc/PID/schedstat
@@ -2484,6 +2516,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_KALLSYMS
INF("wchan", S_IRUGO, proc_pid_wchan),
#endif
+#ifdef CONFIG_STACKTRACE
+ ONE("stack", S_IRUSR, proc_pid_stack),
+#endif
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, proc_pid_schedstat),
#endif
@@ -2819,6 +2854,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_KALLSYMS
INF("wchan", S_IRUGO, proc_pid_wchan),
#endif
+#ifdef CONFIG_STACKTRACE
+ ONE("stack", S_IRUSR, proc_pid_stack),
+#endif
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, proc_pid_schedstat),
#endif
--
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