diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c index 6dd6f0490c3a..6d92b7ef0a55 100644 --- a/drivers/staging/android/logger.c +++ b/drivers/staging/android/logger.c @@ -242,16 +242,28 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len) } /* - * clock_interval - is a < c < b in mod-space? Put another way, does the line - * from a to b cross c? + * is_between - is a < c < b, accounting for wrapping of a, b, and c + * positions in the buffer + * + * That is, if ab, check for c outside (not between) a and b + * + * |------- a xxxxxxxx b --------| + * c^ + * + * |xxxxx b --------- a xxxxxxxxx| + * c^ + * or c^ */ -static inline int clock_interval(size_t a, size_t b, size_t c) +static inline int is_between(size_t a, size_t b, size_t c) { - if (b < a) { - if (a < c || b >= c) + if (a < b) { + /* is c between a and b? */ + if (a < c && c <= b) return 1; } else { - if (a < c && b >= c) + /* is c outside of b through a? */ + if (c <= b || a < c) return 1; } @@ -272,11 +284,11 @@ static void fix_up_readers(struct logger_log *log, size_t len) size_t new = logger_offset(log, old + len); struct logger_reader *reader; - if (clock_interval(old, new, log->head)) + if (is_between(old, new, log->head)) log->head = get_next_entry(log, log->head, len); list_for_each_entry(reader, &log->readers, list) - if (clock_interval(old, new, reader->r_off)) + if (is_between(old, new, reader->r_off)) reader->r_off = get_next_entry(log, reader->r_off, len); }