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Fix printing incorrect panic string issue 

Since the panic_on_oops is disabled, when getting a BUG hit in the code,
the system continues and does not panic. However, a short time later, a
hard lockup is hit and the system does panic. Even though the system
panicked at hard lockup, the panic string is still the first BUG hit.
For example:

Without the patch:
  crash> sys | grep PANIC
         PANIC: "BUG: unable to handle kernel paging request at ffffab835d7f9d50"

With the patch:
  crash> sys | grep PANIC
         PANIC: "Kernel panic - not syncing: Hard LOCKUP"

Let's search for the panic string based on the severity of the panic
event, and also refactor the get_panicmsg() a little bit to improve
readability.

Reported-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
This commit is contained in:
Lianbo Jiang 2023-11-13 19:09:08 +08:00 committed by Kazuhito Hagio
parent 55a43bcefa
commit 262b1c71b4
1 changed files with 39 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

102
task.c
View File

@ -6301,6 +6301,31 @@ get_active_task(int cpu)
return NO_TASK;
}
/*
* Arrange the panic strings based on the severity of the panic
* events.
*/
static const char* panic_msg[] = {
"SysRq : Crash",
"SysRq : Trigger a crash",
"SysRq : Netdump",
"Kernel panic: ",
"Kernel panic - ",
"Kernel BUG at",
"kernel BUG at",
"Unable to handle kernel paging request",
"Unable to handle kernel NULL pointer dereference",
"BUG: unable to handle kernel ",
"general protection fault: ",
"double fault: ",
"divide error: ",
"stack segment: ",
"[Hardware Error]: ",
"Bad mode in ",
"Oops: ",
};
#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))
/*
* Read the panic string.
@ -6308,7 +6333,7 @@ get_active_task(int cpu)
char *
get_panicmsg(char *buf)
{
int msg_found;
int msg_found, i;
BZERO(buf, BUFSIZE);
msg_found = FALSE;
@ -6332,76 +6357,27 @@ get_panicmsg(char *buf)
* active-task flag appropriately. The message may or
* may not be used as the panic message.
*/
rewind(pc->tmpfile);
while (fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "SysRq : Crash") ||
strstr(buf, "SysRq : Trigger a crash")) {
pc->flags |= SYSRQ;
break;
for (i = 0; i < ARRAY_SIZE(panic_msg); i++) {
rewind(pc->tmpfile);
while (fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, panic_msg[i])) {
msg_found = TRUE;
if (strstr(buf, "SysRq :"))
pc->flags |= SYSRQ;
goto found;
}
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "general protection fault: ") ||
strstr(buf, "double fault: ") ||
strstr(buf, "divide error: ") ||
strstr(buf, "stack segment: ")) {
msg_found = TRUE;
break;
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "SysRq : Netdump") ||
strstr(buf, "SysRq : Crash") ||
strstr(buf, "SysRq : Trigger a crash")) {
pc->flags |= SYSRQ;
msg_found = TRUE;
break;
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "Oops: ") ||
strstr(buf, "Kernel BUG at") ||
strstr(buf, "kernel BUG at") ||
strstr(buf, "Unable to handle kernel paging request") ||
strstr(buf, "Unable to handle kernel NULL pointer dereference") ||
strstr(buf, "BUG: unable to handle kernel "))
msg_found = TRUE;
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "sysrq") &&
symbol_exists("sysrq_pressed")) {
get_symbol_data("sysrq_pressed", sizeof(int),
&msg_found);
break;
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "Kernel panic: ") ||
strstr(buf, "Kernel panic - ")) {
msg_found = TRUE;
break;
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "[Hardware Error]: ")) {
msg_found = TRUE;
break;
}
}
rewind(pc->tmpfile);
while (!msg_found && fgets(buf, BUFSIZE, pc->tmpfile)) {
if (strstr(buf, "Bad mode in ")) {
msg_found = TRUE;
if (strstr(buf, "sysrq") && symbol_exists("sysrq_pressed")) {
get_symbol_data("sysrq_pressed", sizeof(int), &msg_found);
break;
}
}
found:
close_tmpfile();
if (!msg_found)