Messages in this thread Patch in this message | | | Date | Wed, 18 Mar 2009 09:18:38 GMT | From | Thomas Gleixner <> | Subject | [tip:tracing/tasks] tracing: replace the crude (unsigned) -1 hackery |
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Commit-ID: 2c7eea4c62ba090b7f4583c3d7337ea0019be900 Gitweb: http://git.kernel.org/tip/2c7eea4c62ba090b7f4583c3d7337ea0019be900 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Wed, 18 Mar 2009 09:03:19 +0100 Commit: Ingo Molnar <mingo@elte.hu> CommitDate: Wed, 18 Mar 2009 10:10:17 +0100
tracing: replace the crude (unsigned) -1 hackery
Impact: cleanup
The command line recorder uses (unsigned) -1 to mark non mapped entries in the pid to command line maps. The validity check is completely unintuitive: idx >= SAVED_CMDLINES
There is no need for such casting games. Use a constant to mark unmapped entries and check for that constant to make the code readable and understandable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- kernel/trace/trace.c | 13 +++++++------ 1 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7b6043e..ca673c4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -633,6 +633,7 @@ void tracing_reset_online_cpus(struct trace_array *tr) } #define SAVED_CMDLINES 128 +#define NO_CMDLINE_MAP UINT_MAX static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1]; static unsigned map_cmdline_to_pid[SAVED_CMDLINES]; static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN]; @@ -644,8 +645,8 @@ static atomic_t trace_record_cmdline_disabled __read_mostly; static void trace_init_cmdlines(void) { - memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline)); - memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid)); + memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline)); + memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid)); cmdline_idx = 0; } @@ -753,12 +754,12 @@ static void trace_save_cmdline(struct task_struct *tsk) return; idx = map_pid_to_cmdline[tsk->pid]; - if (idx >= SAVED_CMDLINES) { + if (idx == NO_CMDLINE_MAP) { idx = (cmdline_idx + 1) % SAVED_CMDLINES; map = map_cmdline_to_pid[idx]; - if (map <= PID_MAX_DEFAULT) - map_pid_to_cmdline[map] = (unsigned)-1; + if (map != NO_CMDLINE_MAP) + map_pid_to_cmdline[map] = NO_CMDLINE_MAP; map_pid_to_cmdline[tsk->pid] = idx; @@ -786,7 +787,7 @@ void trace_find_cmdline(int pid, char comm[]) __raw_spin_lock(&trace_cmdline_lock); map = map_pid_to_cmdline[pid]; - if (map >= SAVED_CMDLINES) + if (map == NO_CMDLINE_MAP) goto out; strcpy(comm, saved_cmdlines[map]);
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