From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [2/2] ras: close the race condition with timer From: Cong Wang Message-Id: <20190416012001.5338-2-xiyou.wangcong@gmail.com> Date: Mon, 15 Apr 2019 18:20:01 -0700 To: linux-kernel@vger.kernel.org Cc: linux-edac@vger.kernel.org, Cong Wang , Tony Luck , Borislav Petkov , Thomas Gleixner List-ID: Y2VjX3RpbWVyX2ZuKCkgaXMgYSB0aW1lciBjYWxsYmFjayB3aGljaCByZWFkcyBjZV9hcnIuYXJy YXlbXQphbmQgdXBkYXRlcyBpdHMgZGVjYXkgdmFsdWVzLiBFbGVtZW50cyBjb3VsZCBiZSBhZGRl ZCB0byBvcgpyZW1vdmVkIGZyb20gdGhpcyBnbG9iYWwgYXJyYXkgaW4gcGFyYWxsZWwsIGFsdGhv dWdoIHRoZSBhcnJheQppdHNlbGYgd2lsbCBub3QgZ3JvdyBvciBzaHJpbmsuIGRlbF9scnVfZWxl bV91bmxvY2tlZCgpIHVzZXMKRlVMTF9DT1VOVCgpIGFzIGEga2V5IHRvIGZpbmQgYSByaWdodCBl bGVtZW50IHRvIHJlbW92ZSwKd2hpY2ggY291bGQgYmUgYWZmZWN0ZWQgYnkgdGhlIHBhcmFsbGVs IHRpbWVyLgoKRml4IHRoaXMgYnkgY29udmVydGluZyB0aGUgbXV0ZXggdG8gYSBzcGlubG9jayBh bmQgaG9sZGluZyBpdAppbnNpZGUgdGhlIHRpbWVyLgoKRml4ZXM6IDAxMWQ4MjYxMTE3MiAoIlJB UzogQWRkIGEgQ29ycmVjdGVkIEVycm9ycyBDb2xsZWN0b3IiKQpDYzogVG9ueSBMdWNrIDx0b255 Lmx1Y2tAaW50ZWwuY29tPgpDYzogQm9yaXNsYXYgUGV0a292IDxicEBhbGllbjguZGU+CkNjOiBU aG9tYXMgR2xlaXhuZXIgPHRnbHhAbGludXRyb25peC5kZT4KU2lnbmVkLW9mZi1ieTogQ29uZyBX YW5nIDx4aXlvdS53YW5nY29uZ0BnbWFpbC5jb20+Ci0tLQogZHJpdmVycy9yYXMvY2VjLmMgfCAx NiArKysrKysrKystLS0tLS0tCiAxIGZpbGUgY2hhbmdlZCwgOSBpbnNlcnRpb25zKCspLCA3IGRl bGV0aW9ucygtKQoKZGlmZiAtLWdpdCBhL2RyaXZlcnMvcmFzL2NlYy5jIGIvZHJpdmVycy9yYXMv Y2VjLmMKaW5kZXggNjEzMzJjOWFhYjVhLi5hODJjOWQwOGQ0N2EgMTAwNjQ0Ci0tLSBhL2RyaXZl cnMvcmFzL2NlYy5jCisrKyBiL2RyaXZlcnMvcmFzL2NlYy5jCkBAIC0xMTcsNyArMTE3LDcgQEAg c3RhdGljIHN0cnVjdCBjZV9hcnJheSB7CiAJfTsKIH0gY2VfYXJyOwogCi1zdGF0aWMgREVGSU5F X01VVEVYKGNlX211dGV4KTsKK3N0YXRpYyBERUZJTkVfU1BJTkxPQ0soY2VfbG9jayk7CiBzdGF0 aWMgdTY0IGRmc19wZm47CiAKIC8qIEFtb3VudCBvZiBlcnJvcnMgYWZ0ZXIgd2hpY2ggd2Ugb2Zm bGluZSAqLwpAQCAtMTcxLDcgKzE3MSw5IEBAIHN0YXRpYyB2b2lkIGNlY19tb2RfdGltZXIoc3Ry dWN0IHRpbWVyX2xpc3QgKnQsIHVuc2lnbmVkIGxvbmcgaW50ZXJ2YWwpCiAKIHN0YXRpYyB2b2lk IGNlY190aW1lcl9mbihzdHJ1Y3QgdGltZXJfbGlzdCAqdW51c2VkKQogeworCXNwaW5fbG9jaygm Y2VfbG9jayk7CiAJZG9fc3ByaW5nX2NsZWFuaW5nKCZjZV9hcnIpOworCXNwaW5fdW5sb2NrKCZj ZV9sb2NrKTsKIAogCWNlY19tb2RfdGltZXIoJmNlY190aW1lciwgdGltZXJfaW50ZXJ2YWwpOwog fQpAQCAtMjY1LDkgKzI2Nyw5IEBAIHN0YXRpYyB1NjQgX19tYXliZV91bnVzZWQgZGVsX2xydV9l bGVtKHZvaWQpCiAJaWYgKCFjYS0+bikKIAkJcmV0dXJuIDA7CiAKLQltdXRleF9sb2NrKCZjZV9t dXRleCk7CisJc3Bpbl9sb2NrX2JoKCZjZV9sb2NrKTsKIAlwZm4gPSBkZWxfbHJ1X2VsZW1fdW5s b2NrZWQoY2EpOwotCW11dGV4X3VubG9jaygmY2VfbXV0ZXgpOworCXNwaW5fdW5sb2NrX2JoKCZj ZV9sb2NrKTsKIAogCXJldHVybiBwZm47CiB9CkBAIC0yODgsNyArMjkwLDcgQEAgaW50IGNlY19h ZGRfZWxlbSh1NjQgcGZuKQogCiAJY2EtPmNlc19lbnRlcmVkKys7CiAKLQltdXRleF9sb2NrKCZj ZV9tdXRleCk7CisJc3Bpbl9sb2NrX2JoKCZjZV9sb2NrKTsKIAogCWlmIChjYS0+biA9PSBNQVhf RUxFTVMpCiAJCVdBUk5fT04oIWRlbF9scnVfZWxlbV91bmxvY2tlZChjYSkpOwpAQCAtMzQ5LDcg KzM1MSw3IEBAIGludCBjZWNfYWRkX2VsZW0odTY0IHBmbikKIAkJZG9fc3ByaW5nX2NsZWFuaW5n KGNhKTsKIAogdW5sb2NrOgotCW11dGV4X3VubG9jaygmY2VfbXV0ZXgpOworCXNwaW5fdW5sb2Nr X2JoKCZjZV9sb2NrKTsKIAogCXJldHVybiByZXQ7CiB9CkBAIC00MDYsNyArNDA4LDcgQEAgc3Rh dGljIGludCBhcnJheV9kdW1wKHN0cnVjdCBzZXFfZmlsZSAqbSwgdm9pZCAqdikKIAl1NjQgcHJl diA9IDA7CiAJaW50IGk7CiAKLQltdXRleF9sb2NrKCZjZV9tdXRleCk7CisJc3Bpbl9sb2NrX2Jo KCZjZV9sb2NrKTsKIAogCXNlcV9wcmludGYobSwgInsgbjogJWRcbiIsIGNhLT5uKTsKIAlmb3Ig KGkgPSAwOyBpIDwgY2EtPm47IGkrKykgewpAQCAtNDMxLDcgKzQzMyw3IEBAIHN0YXRpYyBpbnQg YXJyYXlfZHVtcChzdHJ1Y3Qgc2VxX2ZpbGUgKm0sIHZvaWQgKnYpCiAKIAlzZXFfcHJpbnRmKG0s ICJBY3Rpb24gdGhyZXNob2xkOiAlZFxuIiwgY291bnRfdGhyZXNob2xkKTsKIAotCW11dGV4X3Vu bG9jaygmY2VfbXV0ZXgpOworCXNwaW5fdW5sb2NrX2JoKCZjZV9sb2NrKTsKIAogCXJldHVybiAw OwogfQo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E336CC282DA for ; 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Mon, 15 Apr 2019 18:20:19 -0700 (PDT) Received: from tw-172-25-31-76.office.twttr.net ([8.25.197.24]) by smtp.gmail.com with ESMTPSA id a85sm64206995pfa.166.2019.04.15.18.20.17 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Apr 2019 18:20:18 -0700 (PDT) From: Cong Wang To: linux-kernel@vger.kernel.org Cc: linux-edac@vger.kernel.org, Cong Wang , Tony Luck , Borislav Petkov , Thomas Gleixner Subject: [PATCH 2/2] ras: close the race condition with timer Date: Mon, 15 Apr 2019 18:20:01 -0700 Message-Id: <20190416012001.5338-2-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190416012001.5338-1-xiyou.wangcong@gmail.com> References: <20190416012001.5338-1-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Message-ID: <20190416012001.qyGGFYe4Uui8XgyeLXWV1quKyk9R9JV-L-h30gkjAfY@z> cec_timer_fn() is a timer callback which reads ce_arr.array[] and updates its decay values. Elements could be added to or removed from this global array in parallel, although the array itself will not grow or shrink. del_lru_elem_unlocked() uses FULL_COUNT() as a key to find a right element to remove, which could be affected by the parallel timer. Fix this by converting the mutex to a spinlock and holding it inside the timer. Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector") Cc: Tony Luck Cc: Borislav Petkov Cc: Thomas Gleixner Signed-off-by: Cong Wang --- drivers/ras/cec.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c index 61332c9aab5a..a82c9d08d47a 100644 --- a/drivers/ras/cec.c +++ b/drivers/ras/cec.c @@ -117,7 +117,7 @@ static struct ce_array { }; } ce_arr; -static DEFINE_MUTEX(ce_mutex); +static DEFINE_SPINLOCK(ce_lock); static u64 dfs_pfn; /* Amount of errors after which we offline */ @@ -171,7 +171,9 @@ static void cec_mod_timer(struct timer_list *t, unsigned long interval) static void cec_timer_fn(struct timer_list *unused) { + spin_lock(&ce_lock); do_spring_cleaning(&ce_arr); + spin_unlock(&ce_lock); cec_mod_timer(&cec_timer, timer_interval); } @@ -265,9 +267,9 @@ static u64 __maybe_unused del_lru_elem(void) if (!ca->n) return 0; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); pfn = del_lru_elem_unlocked(ca); - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return pfn; } @@ -288,7 +290,7 @@ int cec_add_elem(u64 pfn) ca->ces_entered++; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); if (ca->n == MAX_ELEMS) WARN_ON(!del_lru_elem_unlocked(ca)); @@ -349,7 +351,7 @@ int cec_add_elem(u64 pfn) do_spring_cleaning(ca); unlock: - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return ret; } @@ -406,7 +408,7 @@ static int array_dump(struct seq_file *m, void *v) u64 prev = 0; int i; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); seq_printf(m, "{ n: %d\n", ca->n); for (i = 0; i < ca->n; i++) { @@ -431,7 +433,7 @@ static int array_dump(struct seq_file *m, void *v) seq_printf(m, "Action threshold: %d\n", count_threshold); - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return 0; } -- 2.20.1