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kdb: Don't back trace on a cpu that didn't round up

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If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL.  Let's add a check.
It's wise to also set the task to NULL when leaving the debugger so
that if we fail to round up on a later entry into the debugger we
won't backtrace a stale task.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
This commit is contained in:
Douglas Anderson
2018-12-04 19:38:28 -08:00
committed by Daniel Thompson
parent 87b0959285
commit 162bc7f5af
3 changed files with 14 additions and 8 deletions
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11
kernel/debug/kdb/kdb_bt.c
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@@ -186,7 +186,16 @@ kdb_bt(int argc, const char **argv)
kdb_printf("btc: cpu status: ");
kdb_parse("cpu\n");
for_each_online_cpu(cpu) {
sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
void *kdb_tsk = KDB_TSK(cpu);
/* If a CPU failed to round up we could be here */
if (!kdb_tsk) {
kdb_printf("WARNING: no task for cpu %ld\n",
cpu);
continue;
}
sprintf(buf, "btt 0x%px\n", kdb_tsk);
kdb_parse(buf);
touch_nmi_watchdog();
}