Messages in this thread Patch in this message | | | From | Song Liu <> | Subject | Re: [PATCH v5 bpf-next 2/4] ftrace: Allow IPMODIFY and DIRECT ops on the same function | Date | Fri, 9 Sep 2022 14:05:27 +0000 |
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> On Sep 9, 2022, at 4:58 AM, Naveen N. Rao <naveen.n.rao@linux.ibm.com> wrote: > > Song Liu wrote:
[...]
>> + >> /** >> * register_ftrace_function - register a function for profiling >> * @ops: ops structure that holds the function for profiling. >> @@ -8018,14 +8206,15 @@ int register_ftrace_function(struct ftrace_ops *ops) >> { >> int ret; >> - ftrace_ops_init(ops); >> - >> - mutex_lock(&ftrace_lock); >> - >> - ret = ftrace_startup(ops, 0); >> + lock_direct_mutex(); > > Trying to enable ftrace direct on powerpc, this is resulting in a hung task when testing samples/ftrace/ftrace-direct-modify.c > > Essentially, the sample calls modify_ftrace_direct(), which grabs direct_mutex before calling ftrace_modify_direct_caller()->register_ftrace_function(). >
Thanks for the report. Would the following change fix the issue?
Song
diff --git i/kernel/trace/ftrace.c w/kernel/trace/ftrace.c index bc921a3f7ea8..2f1e6cfa834e 100644 --- i/kernel/trace/ftrace.c +++ w/kernel/trace/ftrace.c @@ -5496,7 +5496,7 @@ int __weak ftrace_modify_direct_caller(struct ftrace_func_entry *entry, if (ret) goto out_lock;
- ret = register_ftrace_function(&stub_ops); + ret = register_ftrace_function_nolock(&stub_ops); if (ret) { ftrace_set_filter_ip(&stub_ops, ip, 1, 0); goto out_lock; > > - Naveen > > >> + ret = prepare_direct_functions_for_ipmodify(ops); >> + if (ret < 0) >> + goto out_unlock; >> - mutex_unlock(&ftrace_lock); >> + ret = register_ftrace_function_nolock(ops); >> +out_unlock: >> + unlock_direct_mutex(); >> return ret; >> } >> EXPORT_SYMBOL_GPL(register_ftrace_function); >> @@ -8044,6 +8233,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops) >> ret = ftrace_shutdown(ops, 0); >> mutex_unlock(&ftrace_lock); >> + cleanup_direct_functions_after_ipmodify(ops); >> return ret; >> } >> EXPORT_SYMBOL_GPL(unregister_ftrace_function); >> -- >> 2.30.2
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