From patchwork Thu Jun 13 18:34:30 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13697291 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA81A14D420; Thu, 13 Jun 2024 18:34:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718303682; cv=none; b=Hmvk2PoopljImCwhU4SCeSN35kjjmbHp9+TO41BlQ4vbEsjgBmdp+FTULnWRLZ/Ocn40e0DMpj0qT3Xqx5ODdkBeAhEPorkzCCh/lqJfPFu8fXl4gWWUw4D5XrOA/Y2KbdPCKaW9Pq3QOQivWzAZnfFVpzJDfgugKoRqzlyhIRc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718303682; c=relaxed/simple; bh=P0z7CPlefmV2nykZZ/K60TZR1AJ3MxzaUNXJ+hqBQ6M=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=gNQLfPEBcslpiDJmYGVOYfyH9ibhJm8n3X3LBmdUfE4Vv4+wYHF0CQoeCwKjNC8MzYUUY8y+jvaT/xYIXRx+TBy7EAhwTRvDq7bwAKBsOxJfJnpZsVjV/+fUBsutvHXUeUcmPrFw6icuDC2+24oSi9z3j4f5W9J4UW8y9hXikXM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PrfWbtnx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PrfWbtnx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38B7AC32786; Thu, 13 Jun 2024 18:34:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718303682; bh=P0z7CPlefmV2nykZZ/K60TZR1AJ3MxzaUNXJ+hqBQ6M=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=PrfWbtnxSLaOj/jShzfV/Zz8Er0gv11B1Wu2660ohd8gzPkLR1DlwFpvntr7fDqW6 zG5ukM6RxqlPJMf1Gl1zhUJ9Q+opfVYOgMvSx0ZKeNX/5FYXsOfaGsE7NKQvqColpt MwHTMqGzdbJfhIUreMvEgesASjJVbmN+sN6bVno8/z9Z7Cqf2xPchh2tOoTDAnS+Bt 19SsAxex+Kgjv/KbO0eKyA/e72Gmas5mShuthQn7e0OavN3zzubDHqSyA6n0PRZQNX xZ+ilhgtm4CjYCnFpvGth5zWRyC0WcRBpkVbQ9KvYDyE8mc0Wk5/PmAVkXOgigVZwt xwwZQjyj8WnHg== From: Jeff Layton Date: Thu, 13 Jun 2024 14:34:30 -0400 Subject: [PATCH v3 1/5] sunrpc: fix up the special handling of sv_nrpools == 1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240613-nfsd-next-v3-1-3b51c3c2fc59@kernel.org> References: <20240613-nfsd-next-v3-0-3b51c3c2fc59@kernel.org> In-Reply-To: <20240613-nfsd-next-v3-0-3b51c3c2fc59@kernel.org> To: Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Lorenzo Bianconi Cc: Trond Myklebust , Anna Schumaker , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Jeff Layton X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4030; i=jlayton@kernel.org; h=from:subject:message-id; bh=P0z7CPlefmV2nykZZ/K60TZR1AJ3MxzaUNXJ+hqBQ6M=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBmazu+tAFgD3CcatPdHqafaoo+CrTqYJ/+lmSBE f4mbUzukHiJAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZms7vgAKCRAADmhBGVaC FdUUEAC91/Mbies3cnsrpyhHq380clmNMWy+ebmriaiOiQdMwguLWI/SJCX1E9+flCl+vDl0odg R70l6M0PTsC68QYe9zhx3svjA+yUoQfv2ann2+sj2wkASKxsfBVCx4JE7QALOpdaU7YqyyrDpO2 nMkxblsauPl1xbGiyAMmaEnD9P+3lVwszF1fRl3fte6ZA6KxFdPrnzCiPG0Xoj8a4X/XAVPk4ja zZ7RsgApB+sZ1PKwSERvlFBxY00o1xQ+cxf2V40sxfC2JAlt3jnmqMXeApsOuEala779p3r6LhP 3DAsD7Gir9868aLKrgwv139lcdSb9xbjQXFl3V9oFPMQ1H2PB6WKy+8vyhMcuZ8zwRqNknMdeVb 0yqBgl2YeabjZC7CF6SSbEq3VflDBRbUuRfzajhjXKHdH5OwzmGtWpUCSLCAffj2JYedU1skDKa lKHTSJizQ8P75MveB3VI1hF9QO2LxNkIQXTZtwmDNg7cDHuwF5aIxazRN6i4JM0ouKQNI1fFuhQ XrCU74He6bUGh07vM73irKe3ShZQrC32OiL4X/pOfKSKCOaN+mrjTYixeJYqQZiXQMWgwW8fVnv seZvn6ZHI1bniszYpAqdkoikx5Ob/V4JZnD5xAKylp+8E3V8E1cw/WkhZwZYuGVHHjSE3lPcpd1 qaiXpnR6WwgFitQ== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 X-Patchwork-Delegate: kuba@kernel.org Only pooled services take a reference to the svc_pool_map. The sunrpc code has always used the sv_nrpools value to detect whether the service is pooled. The problem there is that nfsd is a pooled service, but when it's running in "global" pool_mode, it doesn't take a reference to the pool map because it has a sv_nrpools value of 1. This means that we have two separate codepaths for starting the server, depending on whether it's pooled or not. Fix this by adding a new flag to the svc_serv, that indicates whether the serv is pooled. With this we can have the nfsd service unconditionally take a reference, regardless of pool_mode. Note that this is a behavior change for /sys/module/sunrpc/parameters/pool_mode. Usually this file does not allow you to change the pool-mode while there are nfsd threads running, but if the pool-mode is "global" it's allowed. My assumption is that this is a bug, since it probably should never have worked this way. This patch changes the behavior such that you get back EBUSY even when nfsd is running in global mode. I think this is more reasonable behavior, and given that most people set this today using the module parameter, it's doubtful anyone will notice. Signed-off-by: Jeff Layton --- include/linux/sunrpc/svc.h | 1 + net/sunrpc/svc.c | 26 +++++++------------------- 2 files changed, 8 insertions(+), 19 deletions(-) diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 23617da0e565..d0433e1642b3 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -85,6 +85,7 @@ struct svc_serv { char * sv_name; /* service name */ unsigned int sv_nrpools; /* number of thread pools */ + bool sv_is_pooled; /* is this a pooled service? */ struct svc_pool * sv_pools; /* array of thread pools */ int (*sv_threadfn)(void *data); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 2b4b1276d4e8..f80d94cbb8b1 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -250,10 +250,8 @@ svc_pool_map_get(void) int npools = -1; mutex_lock(&svc_pool_map_mutex); - if (m->count++) { mutex_unlock(&svc_pool_map_mutex); - WARN_ON_ONCE(m->npools <= 1); return m->npools; } @@ -275,32 +273,21 @@ svc_pool_map_get(void) m->mode = SVC_POOL_GLOBAL; } m->npools = npools; - - if (npools == 1) - /* service is unpooled, so doesn't hold a reference */ - m->count--; - mutex_unlock(&svc_pool_map_mutex); return npools; } /* - * Drop a reference to the global map of cpus to pools, if - * pools were in use, i.e. if npools > 1. + * Drop a reference to the global map of cpus to pools. * When the last reference is dropped, the map data is - * freed; this allows the sysadmin to change the pool - * mode using the pool_mode module option without - * rebooting or re-loading sunrpc.ko. + * freed; this allows the sysadmin to change the pool. */ static void -svc_pool_map_put(int npools) +svc_pool_map_put(void) { struct svc_pool_map *m = &svc_pool_map; - if (npools <= 1) - return; mutex_lock(&svc_pool_map_mutex); - if (!--m->count) { kfree(m->to_pool); m->to_pool = NULL; @@ -308,7 +295,6 @@ svc_pool_map_put(int npools) m->pool_to = NULL; m->npools = 0; } - mutex_unlock(&svc_pool_map_mutex); } @@ -553,9 +539,10 @@ struct svc_serv *svc_create_pooled(struct svc_program *prog, serv = __svc_create(prog, stats, bufsize, npools, threadfn); if (!serv) goto out_err; + serv->sv_is_pooled = true; return serv; out_err: - svc_pool_map_put(npools); + svc_pool_map_put(); return NULL; } EXPORT_SYMBOL_GPL(svc_create_pooled); @@ -585,7 +572,8 @@ svc_destroy(struct svc_serv **servp) cache_clean_deferred(serv); - svc_pool_map_put(serv->sv_nrpools); + if (serv->sv_is_pooled) + svc_pool_map_put(); for (i = 0; i < serv->sv_nrpools; i++) { struct svc_pool *pool = &serv->sv_pools[i];