From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41VVy23gXVzF3Hb for ; Wed, 18 Jul 2018 05:40:58 +1000 (AEST) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6HJd0uS062466 for ; Tue, 17 Jul 2018 15:40:55 -0400 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0b-001b2d01.pphosted.com with ESMTP id 2k9p209h0k-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 17 Jul 2018 15:40:55 -0400 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 17 Jul 2018 15:40:54 -0400 From: John Allen To: linuxppc-dev@lists.ozlabs.org, nfont@linux.vnet.ibm.com Cc: John Allen Subject: [PATCH v2 1/2] powerpc/pseries: Avoid blocking rtas polling handling multiple PRRN events Date: Tue, 17 Jul 2018 14:40:47 -0500 In-Reply-To: <20180717194048.3057-1-jallen@linux.ibm.com> References: <20180717194048.3057-1-jallen@linux.ibm.com> Message-Id: <20180717194048.3057-2-jallen@linux.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When a PRRN event is being handled and another PRRN event comes in, the second event will block rtas polling waiting on the first to complete, preventing any further rtas events from being handled. This can be especially problematic in case that PRRN events are continuously being queued in which case rtas polling gets indefinitely blocked completely. This patch introduces a mutex that prevents any subsequent PRRN events from running while there is a prrn event being handled, allowing rtas polling to continue normally. Signed-off-by: John Allen --- v2: -Unlock prrn_lock when PRRN operations are complete, not after handler is scheduled. -Remove call to flush_work, the previous broken method of serializing PRRN events. --- arch/powerpc/kernel/rtasd.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c index 44d66c33d59d..845fc5aec178 100644 --- a/arch/powerpc/kernel/rtasd.c +++ b/arch/powerpc/kernel/rtasd.c @@ -35,6 +35,8 @@ static DEFINE_SPINLOCK(rtasd_log_lock); +static DEFINE_MUTEX(prrn_lock); + static DECLARE_WAIT_QUEUE_HEAD(rtas_log_wait); static char *rtas_log_buf; @@ -284,15 +286,17 @@ static void prrn_work_fn(struct work_struct *work) */ pseries_devicetree_update(-prrn_update_scope); numa_update_cpu_topology(false); + mutex_unlock(&prrn_lock); } static DECLARE_WORK(prrn_work, prrn_work_fn); static void prrn_schedule_update(u32 scope) { - flush_work(&prrn_work); - prrn_update_scope = scope; - schedule_work(&prrn_work); + if (mutex_trylock(&prrn_lock)) { + prrn_update_scope = scope; + schedule_work(&prrn_work); + } } static void handle_rtas_event(const struct rtas_error_log *log) -- 2.17.1