1. memset(tmp, 0) and especially kzalloc(PATH_MAX) are suboptimal, we only need to zero-fill the alignment.
Remove this memset/__GFP_ZERO and fill the extra bytes by hand. 2. The usage of strncpy(tmp) is not optimal too, we can add the new label and do this in one place. Signed-off-by: Oleg Nesterov <[email protected]> --- kernel/events/core.c | 47 +++++++++++++++++++++++------------------------ 1 files changed, 23 insertions(+), 24 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4a1e7b8..777a268 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5098,20 +5098,17 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) int maj = 0, min = 0; u64 ino = 0, gen = 0; unsigned int size; - char tmp[16]; - char *buf = NULL; - const char *name; - - memset(tmp, 0, sizeof(tmp)); + char tmp[16], *name, *buf = NULL; + const char *str; if (file) { struct inode *inode; dev_t dev; - buf = kzalloc(PATH_MAX, GFP_KERNEL); + buf = kmalloc(PATH_MAX, GFP_KERNEL); if (!buf) { - name = strncpy(tmp, "//enomem", sizeof(tmp)); - goto got_name; + str = "//enomem"; + goto cpy_name; } /* * d_path works from the end of the rb backwards, so we @@ -5120,8 +5117,8 @@ 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; + str = "//toolong"; + goto cpy_name; } inode = file_inode(vma->vm_file); dev = inode->i_sb->s_dev; @@ -5129,32 +5126,34 @@ 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 = arch_vma_name(vma); - if (name) { - name = strncpy(tmp, name, sizeof(tmp) - 1); - tmp[sizeof(tmp) - 1] = '\0'; - goto got_name; - } + str = arch_vma_name(vma); + if (str) + 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; + str = "[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; + str = "[stack]"; + goto cpy_name; } - name = strncpy(tmp, "//anon", sizeof(tmp)); - goto got_name; + str = "//anon"; + goto cpy_name; } +cpy_name: + strlcpy(tmp, str, sizeof(tmp)); + name = tmp; got_name: - size = ALIGN(strlen(name)+1, sizeof(u64)); + size = strlen(name) + 1; + while (size % sizeof(u64)) + name[size++] = '\0'; mmap_event->file_name = name; mmap_event->file_size = size; -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
