svn commit: r339471 - head/sys/kern
Conrad Meyer
cem at FreeBSD.org
Sat Oct 20 18:42:30 UTC 2018
Author: cem
Date: Sat Oct 20 18:42:28 2018
New Revision: 339471
URL: https://svnweb.freebsd.org/changeset/base/339471
Log:
tty info (^T): Add optional kernel stack(9) traces
It is often useful for developers and administrators to determine a running
thread's stack for debugging purposes. With this feature, using ^T will
print that information
For now, the feature is disabled by default. Enable with sysctl
kern.tty_info_kstacks=1.
Discussed with: markj
Reviewed by: oshogbo
Relnotes: yes
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D17621
Modified:
head/sys/kern/tty_info.c
Modified: head/sys/kern/tty_info.c
==============================================================================
--- head/sys/kern/tty_info.c Sat Oct 20 18:37:21 2018 (r339470)
+++ head/sys/kern/tty_info.c Sat Oct 20 18:42:28 2018 (r339471)
@@ -49,11 +49,14 @@ __FBSDID("$FreeBSD$");
#include <sys/cons.h>
#include <sys/kdb.h>
#include <sys/lock.h>
+#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sbuf.h>
#include <sys/sched.h>
+#include <sys/stack.h>
+#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/tty.h>
@@ -233,6 +236,11 @@ sbuf_tty_drain(void *a, const char *d, int len)
return (-ENXIO);
}
+static bool tty_info_kstacks = false;
+SYSCTL_BOOL(_kern, OID_AUTO, tty_info_kstacks, CTLFLAG_RWTUN,
+ &tty_info_kstacks, 0,
+ "Enable printing kernel stack(9) traces on ^T (tty info)");
+
/*
* Report on state of foreground process group.
*/
@@ -240,12 +248,13 @@ void
tty_info(struct tty *tp)
{
struct timeval rtime, utime, stime;
+ struct stack stack;
struct proc *p, *ppick;
struct thread *td, *tdpick;
const char *stateprefix, *state;
struct sbuf sb;
long rss;
- int load, pctcpu;
+ int load, pctcpu, sterr;
pid_t pid;
char comm[MAXCOMLEN + 1];
struct rusage ru;
@@ -320,6 +329,15 @@ tty_info(struct tty *tp)
else
state = "unknown";
pctcpu = (sched_pctcpu(td) * 10000 + FSCALE / 2) >> FSHIFT;
+ if (tty_info_kstacks) {
+ stack_zero(&stack);
+ if (TD_IS_SWAPPED(td) || TD_IS_RUNNING(td))
+ sterr = stack_save_td_running(&stack, td);
+ else {
+ stack_save_td(&stack, td);
+ sterr = 0;
+ }
+ }
thread_unlock(td);
if (p->p_state == PRS_NEW || p->p_state == PRS_ZOMBIE)
rss = 0;
@@ -340,6 +358,9 @@ tty_info(struct tty *tp)
(long)utime.tv_sec, utime.tv_usec / 10000,
(long)stime.tv_sec, stime.tv_usec / 10000,
pctcpu / 100, rss);
+
+ if (tty_info_kstacks && sterr == 0)
+ stack_sbuf_print_flags(&sb, &stack, M_NOWAIT);
out:
sbuf_finish(&sb);
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