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Two tracing fixes:

Browse Source 
- Fix temp buffer accounting that caused a WARNING for
   ftrace_dump_on_opps()
 
 - Move the recursion check in one of the function callback helpers to the
   beginning of the function, as if the rcu_is_watching() gets traced, it
   will cause a recursive loop that will crash the kernel.
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Merge tag 'trace-v5.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Two tracing fixes:

   - Fix temp buffer accounting that caused a WARNING for
     ftrace_dump_on_opps()

   - Move the recursion check in one of the function callback helpers to
     the beginning of the function, as if the rcu_is_watching() gets
     traced, it will cause a recursive loop that will crash the kernel"

* tag 'trace-v5.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Move RCU is watching check after recursion check
  tracing: Fix trace_find_next_entry() accounting of temp buffer size
This commit is contained in:
Linus Torvalds 2020-10-01 09:41:02 -07:00
commit aa5ff93523
2 changed files with 8 additions and 8 deletions
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6
kernel/trace/ftrace.c
View File

@ -6993,16 +6993,14 @@ static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
{
int bit;
if ((op->flags & FTRACE_OPS_FL_RCU) && !rcu_is_watching())
return;
bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
if (bit < 0)
return;
preempt_disable_notrace();
op->func(ip, parent_ip, op, regs);
if (!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching())
op->func(ip, parent_ip, op, regs);
preempt_enable_notrace();
trace_clear_recursion(bit);

10
kernel/trace/trace.c
View File

@ -3546,13 +3546,15 @@ struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
if (iter->ent && iter->ent != iter->temp) {
if ((!iter->temp || iter->temp_size < iter->ent_size) &&
!WARN_ON_ONCE(iter->temp == static_temp_buf)) {
kfree(iter->temp);
iter->temp = kmalloc(iter->ent_size, GFP_KERNEL);
if (!iter->temp)
void *temp;
temp = kmalloc(iter->ent_size, GFP_KERNEL);
if (!temp)
return NULL;
kfree(iter->temp);
iter->temp = temp;
iter->temp_size = iter->ent_size;
}
memcpy(iter->temp, iter->ent, iter->ent_size);
iter->temp_size = iter->ent_size;
iter->ent = iter->temp;
}
entry = __find_next_entry(iter, ent_cpu, NULL, ent_ts);