perf: Factor out strncpy() in perf_event_mmap_event()

While this is really minor, but strncpy() does the unnecessary
zero-padding till the end of tmp[16] and it is called every time
we are going to use the string literal.

Turn these strncpy()'s into the single strlcpy() under the new
label, saves 72 bytes.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131017182417.GA17753@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 16 insertions, 16 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 17b3c6cf1606..4dc078d18929 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5144,8 +5144,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 
                 buf = kmalloc(PATH_MAX, GFP_KERNEL);
                 if (!buf) {
-                        name = strncpy(tmp, "//enomem", sizeof(tmp));
-                        goto got_name;
+                        name = "//enomem";
+                        goto cpy_name;
                 }
                 /*
                  * d_path() works from the end of the rb backwards, so we
@@ -5154,8 +5154,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
                  */
                 name = d_path(&file->f_path, buf, PATH_MAX - sizeof(u64));
                 if (IS_ERR(name)) {
-                        name = strncpy(tmp, "//toolong", sizeof(tmp));
-                        goto got_name;
+                        name = "//toolong";
+                        goto cpy_name;
                 }
                 inode = file_inode(vma->vm_file);
                 dev = inode->i_sb->s_dev;
@@ -5163,30 +5163,30 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
                 gen = inode->i_generation;
                 maj = MAJOR(dev);
                 min = MINOR(dev);
-
+                goto got_name;
         } else {
                 name = (char *)arch_vma_name(vma);
-                if (name) {
-                        name = strncpy(tmp, name, sizeof(tmp) - 1);
-                        tmp[sizeof(tmp) - 1] = '\0';
-                        goto got_name;
-                }
+                if (name)
+                        goto cpy_name;
 
                 if (vma->vm_start <= vma->vm_mm->start_brk &&
                                 vma->vm_end >= vma->vm_mm->brk) {
-                        name = strncpy(tmp, "[heap]", sizeof(tmp));
-                        goto got_name;
+                        name = "[heap]";
+                        goto cpy_name;
                 }
                 if (vma->vm_start <= vma->vm_mm->start_stack &&
                                 vma->vm_end >= vma->vm_mm->start_stack) {
-                        name = strncpy(tmp, "[stack]", sizeof(tmp));
-                        goto got_name;
+                        name = "[stack]";
+                        goto cpy_name;
                 }
 
-                name = strncpy(tmp, "//anon", sizeof(tmp));
-                goto got_name;
+                name = "//anon";
+                goto cpy_name;
         }
 
+cpy_name:
+        strlcpy(tmp, name, sizeof(tmp));
+        name = tmp;
 got_name:
         /*
          * Since our buffer works in 8 byte units we need to align our string