From 9cf79d115f0d161b63161650f14ff903e4c57937 Mon Sep 17 00:00:00 2001 From: Sudeep Holla Date: Thu, 25 Jun 2015 15:02:17 -0700 Subject: [PATCH] bitmap: remove explicit newline handling using scnprintf format string bitmap_print_to_pagebuf uses scnprintf to copy the cpumask/list to page buffer. It handles the newline and trailing null character explicitly. It's unnecessary and also partially duplicated as scnprintf already adds trailing null character. The newline can be passed through format string to scnprintf. This patch does that simplification. However theoretically there's one behavior difference: when the buffer is too small, the original code would still output '\n' at the end while the new code(with this patch) would just continue to print the formatted string. Since this function is dealing with only page buffers, it's highly unlikely to hit that corner case. This patch will help in auditing the users of bitmap_print_to_pagebuf to verify that the buffer passed is large enough and get rid of it completely by replacing them with direct scnprintf() [akpm@linux-foundation.org: tweak comment] Signed-off-by: Sudeep Holla Suggested-by: Pawel Moll Cc: Tejun Heo Cc: "Peter Zijlstra (Intel)" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/bitmap.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index 40162f87ea2d..a578a0189199 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -462,19 +462,20 @@ EXPORT_SYMBOL(bitmap_parse_user); * Output format is a comma-separated list of decimal numbers and * ranges if list is specified or hex digits grouped into comma-separated * sets of 8 digits/set. Returns the number of characters written to buf. + * + * It is assumed that @buf is a pointer into a PAGE_SIZE area and that + * sufficient storage remains at @buf to accommodate the + * bitmap_print_to_pagebuf() output. */ int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp, int nmaskbits) { - ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2; + ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf; int n = 0; - if (len > 1) { - n = list ? scnprintf(buf, len, "%*pbl", nmaskbits, maskp) : - scnprintf(buf, len, "%*pb", nmaskbits, maskp); - buf[n++] = '\n'; - buf[n] = '\0'; - } + if (len > 1) + n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) : + scnprintf(buf, len, "%*pb\n", nmaskbits, maskp); return n; } EXPORT_SYMBOL(bitmap_print_to_pagebuf); -- GitLab