Attached patch implements a /proc/#/wchan which provides a pre-decoded
wchan via kallsyms. I.e.,
[01:47:26]rml@phantasy:~$ cat /proc/712/wchan
wait4
Which is damn nifty and will let ps(1) grab wchan information
without having to parse System.map - in fact, procps will no longer need
System.map at all.
If CONFIG_KALLSYMS is enabled, /proc/#/wchan exists and exports the
pre-decoded symbol name. If it does not exist, neither does the file.
The old interface in /proc/#/stat exists either way, per a suggestion
from Christoph. I am not sure I agree (I would like to avoid the
get_wchan() in stat if CONFIG_KALLSYMS is set) but for now I agree this
is less invasive.
The procps patch is available at:
http://tech9.net/rml/procps/patches/procps-wchan-rml-2.0.10.20021011-1.patch
and ready for merging into procps CVS.
Patch is against 2.5.44. Whoever is one of the secret, mysterious,
incredibly handsome freeze integrators, please apply. :)
Robert Love
Documentation/filesystems/proc.txt | 1 +
fs/proc/base.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 34 insertions(+)
diff -urN linux-2.5.44/Documentation/filesystems/proc.txt linux/Documentation/filesystems/proc.txt
--- linux-2.5.44/Documentation/filesystems/proc.txt 2002-10-19 00:01:19.000000000 -0400
+++ linux/Documentation/filesystems/proc.txt 2002-10-22 01:39:33.000000000 -0400
@@ -130,6 +130,7 @@
stat Process status
statm Process memory status information
status Process status in human readable form
+ wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
..............................................................................
For example, to get the status information of a process, all you have to do is
diff -urN linux-2.5.44/fs/proc/base.c linux/fs/proc/base.c
--- linux-2.5.44/fs/proc/base.c 2002-10-19 00:02:00.000000000 -0400
+++ linux/fs/proc/base.c 2002-10-22 01:39:33.000000000 -0400
@@ -28,6 +28,7 @@
#include <linux/namespace.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
+#include <linux/kallsyms.h>
/*
* For hysterical raisins we keep the same inumbers as in the old procfs.
@@ -54,6 +55,7 @@
PROC_PID_MAPS,
PROC_PID_CPU,
PROC_PID_MOUNTS,
+ PROC_PID_WCHAN,
PROC_PID_FD_DIR = 0x8000, /* 0x8000-0xffff */
};
@@ -81,6 +83,9 @@
E(PROC_PID_ROOT, "root", S_IFLNK|S_IRWXUGO),
E(PROC_PID_EXE, "exe", S_IFLNK|S_IRWXUGO),
E(PROC_PID_MOUNTS, "mounts", S_IFREG|S_IRUGO),
+#ifdef CONFIG_KALLSYMS
+ E(PROC_PID_WCHAN, "wchan", S_IFREG|S_IRUGO),
+#endif
{0,0,NULL,0}
};
#undef E
@@ -245,6 +250,28 @@
return res;
}
+#ifdef CONFIG_KALLSYMS
+/*
+ * Provides a wchan file via kallsyms in a proper one-value-per-file format.
+ * Returns the resolved symbol. If that fails, simply return the address.
+ */
+static int proc_pid_wchan(struct task_struct *task, char *buffer)
+{
+ const char *sym_name, *ignore;
+ unsigned long wchan, dummy;
+
+ wchan = get_wchan(task);
+
+ if (!kallsyms_address_to_symbol(wchan, &ignore, &dummy, &dummy,
+ &ignore, &dummy, &dummy, &sym_name,
+ &dummy, &dummy)) {
+ return sprintf(buffer, "%lu", wchan);
+ }
+
+ return sprintf(buffer, "%s", sym_name);
+}
+#endif
+
/************************************************************************/
/* Here the fs part begins */
/************************************************************************/
@@ -1016,6 +1043,12 @@
case PROC_PID_MOUNTS:
inode->i_fop = &proc_mounts_operations;
break;
+#ifdef CONFIG_KALLSYMS
+ case PROC_PID_WCHAN:
+ inode->i_fop = &proc_info_file_operations;
+ ei->op.proc_read = proc_pid_wchan;
+ break;
+#endif
default:
printk("procfs: impossible type (%d)",p->type);
iput(inode);