From a4e74fa5f0d3e2a11f2d0deb522681d219a81426 Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Fri, 31 Jul 2020 10:17:20 +0200 Subject: [PATCH] kcsan: Simplify constant string handling Simplify checking prefixes and length calculation of constant strings. For the former, the kernel provides str_has_prefix(), and the latter we should just use strlen("..") because GCC and Clang have optimizations that optimize these into constants. No functional change intended. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney --- kernel/kcsan/debugfs.c | 8 ++++---- kernel/kcsan/report.c | 4 ++-- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c index 3a9566addeff..116bdd8f050c 100644 --- a/kernel/kcsan/debugfs.c +++ b/kernel/kcsan/debugfs.c @@ -300,16 +300,16 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o WRITE_ONCE(kcsan_enabled, true); } else if (!strcmp(arg, "off")) { WRITE_ONCE(kcsan_enabled, false); - } else if (!strncmp(arg, "microbench=", sizeof("microbench=") - 1)) { + } else if (str_has_prefix(arg, "microbench=")) { unsigned long iters; - if (kstrtoul(&arg[sizeof("microbench=") - 1], 0, &iters)) + if (kstrtoul(&arg[strlen("microbench=")], 0, &iters)) return -EINVAL; microbenchmark(iters); - } else if (!strncmp(arg, "test=", sizeof("test=") - 1)) { + } else if (str_has_prefix(arg, "test=")) { unsigned long iters; - if (kstrtoul(&arg[sizeof("test=") - 1], 0, &iters)) + if (kstrtoul(&arg[strlen("test=")], 0, &iters)) return -EINVAL; test_thread(iters); } else if (!strcmp(arg, "whitelist")) { diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index 3e83a69239fa..bf1d59449805 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -279,8 +279,8 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries cur = strnstr(buf, "kcsan_", len); if (cur) { - cur += sizeof("kcsan_") - 1; - if (strncmp(cur, "test", sizeof("test") - 1)) + cur += strlen("kcsan_"); + if (!str_has_prefix(cur, "test")) continue; /* KCSAN runtime function. */ /* KCSAN related test. */ }