diff options
| author |   Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-02-22 16:14:17 -0500 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-03-18 10:32:57 -0400 |
| commit | e8b737bfb16a0d540413173e8d1574e3bf8cc0e9 (patch) | |
| tree | 8628e4a3dcf7e54564ceb4e487cbcb1cdbd3863b /include/trace | |
| parent | tracing: Rework __assign_str() and __string() to not duplicate getting the string (diff) | |
| download | wireguard-linux-e8b737bfb16a0d540413173e8d1574e3bf8cc0e9.tar.xz wireguard-linux-e8b737bfb16a0d540413173e8d1574e3bf8cc0e9.zip | |
tracing: Do not calculate strlen() twice for __string() fields
The TRACE_EVENT() macro handles dynamic strings by having:
TP_PROTO(struct some_struct *s),
TP_ARGS(s),
TP_STRUCT__entry(
__string(my_string, s->string)
),
TP_fast_assign(
__assign_str(my_string, s->string);
)
TP_printk("%s", __get_str(my_string))
There's even some code that may call a function helper to find the
s->string value. The problem with the above is that the work to get the
s->string is done twice. Once at the __string() and again in the
__assign_str().
The length of the string is calculated via a strlen(), not once, but
twice. Once during the __string() macro and again in __assign_str(). But
the length is actually already recorded in the data location and here's no
reason to call strlen() again.
Just use the saved length that was saved in the __string() code for the
__assign_str() code.
Link: https://lore.kernel.org/linux-trace-kernel/20240222211442.793074999@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/stages/stage6_event_callback.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index b3e2f321e787..c0e5d097324e 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -32,8 +32,9 @@ #undef __assign_str #define __assign_str(dst, src) \ - strcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? \ - __data_offsets.dst##_ptr_ : "(null)") + memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? \ + __data_offsets.dst##_ptr_ : "(null)", \ + __get_dynamic_array_len(dst)) #undef __assign_str_len #define __assign_str_len(dst, src, len) \ @@ -94,8 +95,9 @@ #undef __assign_rel_str #define __assign_rel_str(dst, src) \ - strcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? \ - __data_offsets.dst##_ptr_ : "(null)") + memcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? \ + __data_offsets.dst##_ptr_ : "(null)", \ + __get_rel_dynamic_array_len(dst)) #undef __assign_rel_str_len #define __assign_rel_str_len(dst, src, len) \ |