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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>
This commit is contained in:
Oleg Nesterov 2013-10-17 20:24:17 +02:00 committed by Ingo Molnar
parent a94d342b9c
commit c7e548b45c
1 changed files with 16 additions and 16 deletions
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32
kernel/events/core.c
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@ -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