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Commit c7e548b4 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131017182417.GA17753@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a94d342b

kernel/events/core.c

+16 −16
Original line number Diff line number Diff line
@@ -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