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>
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a94d342b9c
Коммит
c7e548b45c
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@ -5144,8 +5144,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
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buf = kmalloc(PATH_MAX, GFP_KERNEL);
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if (!buf) {
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name = strncpy(tmp, "//enomem", sizeof(tmp));
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goto got_name;
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name = "//enomem";
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goto cpy_name;
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}
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/*
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* d_path() works from the end of the rb backwards, so we
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@ -5154,8 +5154,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
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*/
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name = d_path(&file->f_path, buf, PATH_MAX - sizeof(u64));
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if (IS_ERR(name)) {
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name = strncpy(tmp, "//toolong", sizeof(tmp));
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goto got_name;
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name = "//toolong";
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goto cpy_name;
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}
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inode = file_inode(vma->vm_file);
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dev = inode->i_sb->s_dev;
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@ -5163,30 +5163,30 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
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gen = inode->i_generation;
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maj = MAJOR(dev);
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min = MINOR(dev);
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goto got_name;
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} else {
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name = (char *)arch_vma_name(vma);
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if (name) {
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name = strncpy(tmp, name, sizeof(tmp) - 1);
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tmp[sizeof(tmp) - 1] = '\0';
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goto got_name;
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}
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if (name)
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goto cpy_name;
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if (vma->vm_start <= vma->vm_mm->start_brk &&
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vma->vm_end >= vma->vm_mm->brk) {
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name = strncpy(tmp, "[heap]", sizeof(tmp));
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goto got_name;
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name = "[heap]";
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goto cpy_name;
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}
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if (vma->vm_start <= vma->vm_mm->start_stack &&
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vma->vm_end >= vma->vm_mm->start_stack) {
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name = strncpy(tmp, "[stack]", sizeof(tmp));
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goto got_name;
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name = "[stack]";
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goto cpy_name;
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}
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name = strncpy(tmp, "//anon", sizeof(tmp));
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goto got_name;
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name = "//anon";
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goto cpy_name;
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}
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cpy_name:
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strlcpy(tmp, name, sizeof(tmp));
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name = tmp;
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got_name:
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/*
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* Since our buffer works in 8 byte units we need to align our string
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