diff options
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/trace_events/trace-events-sample.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h index 13a35f7cbe66..e61471ab7d14 100644 --- a/samples/trace_events/trace-events-sample.h +++ b/samples/trace_events/trace-events-sample.h @@ -141,6 +141,33 @@ * In most cases, the __assign_str() macro will take the same * parameters as the __string() macro had to declare the string. * + * __string_len: This is a helper to a __dynamic_array, but it understands + * that the array has characters in it, and with the combined + * use of __assign_str_len(), it will allocate 'len' + 1 bytes + * in the ring buffer and add a '\0' to the string. This is + * useful if the string being saved has no terminating '\0' byte. + * It requires that the length of the string is known as it acts + * like a memcpy(). + * + * Declared with: + * + * __string_len(foo, bar, len) + * + * To assign this string, use the helper macro __assign_str_len(). + * + * __assign_str(foo, bar, len); + * + * Then len + 1 is allocated to the ring buffer, and a nul terminating + * byte is added. This is similar to: + * + * memcpy(__get_str(foo), bar, len); + * __get_str(foo)[len] = 0; + * + * The advantage of using this over __dynamic_array, is that it + * takes care of allocating the extra byte on the ring buffer + * for the '\0' terminating byte, and __get_str(foo) can be used + * in the TP_printk(). + * * __bitmask: This is another kind of __dynamic_array, but it expects * an array of longs, and the number of bits to parse. It takes * two parameters (name, nr_bits), where name is the name of the |