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Mon, 31 Aug 2026 17:29:44 -0700 (PDT) Received: from 4470NRD-ASU.ssi.samsung.com ([50.205.20.42]) by smtp.gmail.com with ESMTPSA id 00721157ae682-85e668ce7ecsm63349177b3.34.2026.08.31.17.29.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Aug 2026 17:29:43 -0700 (PDT) From: Anisa Su X-Google-Original-From: Anisa Su To: linux-cxl@vger.kernel.org Cc: benjamin.cheatham@amd.com, icheng@nvidia.com, dave@stgolabs.net, dave.jiang@intel.com, alison.schofield@intel.com, jic23@kernel.org, Anisa Su Subject: [PATCH v2 3/4] cxl/events: Bound the per-log Get Event Records loop Date: Mon, 31 Aug 2026 17:26:56 -0700 Message-ID: <20260901002912.958-4-anisa.su@samsung.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260901002912.958-1-anisa.su@samsung.com> References: <20260901002912.958-1-anisa.su@samsung.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit cxl_mem_get_records_log() re-queries a log until the device reports it empty. A misbehaving device that never stops reporting records keeps the event thread stuck in this loop, and there is no cond_resched() to let anything else on the CPU run. Cap the passes at 128 and reschedule between them. Each pass gets up to a full mailbox payload of records from the log, so the cap is a generous upper bound. Report hitting the cap as an error and let the caller give up on the log. Fixes: 6ebe28f9ec72 ("cxl/mem: Read, trace, and clear events on driver load") Signed-off-by: Anisa Su --- drivers/cxl/core/mbox.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index 02b8c33a74b6..5e49589727d5 100644 --- a/drivers/cxl/core/mbox.c +++ b/drivers/cxl/core/mbox.c @@ -1071,6 +1071,8 @@ static int cxl_clear_event_record(struct cxl_memdev_state *mds, return cxl_event_retry_rc(&mbox_cmd, rc); } +#define CXL_EVENT_LOG_MAX_PASSES 128 + static int cxl_mem_get_records_log(struct cxl_memdev_state *mds, enum cxl_event_log_type type, bool *got_records) { @@ -1079,6 +1081,7 @@ static int cxl_mem_get_records_log(struct cxl_memdev_state *mds, struct device *dev = mds->cxlds.dev; struct cxl_get_event_payload *payload; u8 log_type = type; + int passes = 0; u16 nr_rec; int rc = 0; @@ -1134,6 +1137,15 @@ static int cxl_mem_get_records_log(struct cxl_memdev_state *mds, type, rc); break; } + + if (++passes == CXL_EVENT_LOG_MAX_PASSES) { + dev_warn_ratelimited(dev, + "Event log '%d': Still reporting records after %d passes, giving up", + type, passes); + rc = -EIO; + break; + } + cond_resched(); } while (nr_rec); mutex_unlock(&mds->event.log_lock); -- 2.43.0