From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out.google.com (smtp-out.google.com [74.125.121.67]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 44ED4100A2D for ; Wed, 9 Nov 2011 06:30:22 +1100 (EST) Received: from hpaq12.eem.corp.google.com (hpaq12.eem.corp.google.com [172.25.149.12]) by smtp-out.google.com with ESMTP id pA8JUJaf018886 for ; Tue, 8 Nov 2011 11:30:19 -0800 Received: from miche.sea.corp.google.com (miche.sea.corp.google.com [172.31.71.52]) by hpaq12.eem.corp.google.com with ESMTP id pA8JUHqu028151 for ; Tue, 8 Nov 2011 11:30:17 -0800 Received: from miche.sea.corp.google.com (localhost [IPv6:::1]) by miche.sea.corp.google.com (Postfix) with ESMTP id 3146D20253 for ; Tue, 8 Nov 2011 11:30:17 -0800 (PST) Subject: [PATCH v2 2/3] hvc_init(): Enforce one-time initialization. To: ppc-dev From: Miche Baker-Harvey Date: Tue, 08 Nov 2011 11:30:17 -0800 Message-ID: <20111108193016.30707.95497.stgit@miche.sea.corp.google.com> In-Reply-To: <20111108193005.30707.23990.stgit@miche.sea.corp.google.com> References: <20111108193005.30707.23990.stgit@miche.sea.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , hvc_init() must only be called once, and no thread should continue with hvc_alloc() until after initialization is complete. The original code does not enforce either of these requirements. A new mutex limits entry to hvc_init() to a single thread, and blocks all later comers until it has completed. This patch fixes multiple crash symptoms. Signed-off-by: Miche Baker-Harvey --- drivers/tty/hvc/hvc_console.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index b6b2d18..09a6159 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -29,8 +29,9 @@ #include #include #include -#include #include +#include +#include #include #include #include @@ -84,6 +85,10 @@ static LIST_HEAD(hvc_structs); * list traversal. */ static DEFINE_SPINLOCK(hvc_structs_lock); +/* + * only one task does allocation at a time. + */ +static DEFINE_MUTEX(hvc_ports_mutex); /* * This value is used to assign a tty->index value to a hvc_struct based @@ -825,11 +830,15 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, int i; /* We wait until a driver actually comes along */ + mutex_lock(&hvc_ports_mutex); if (!hvc_driver) { int err = hvc_init(); - if (err) + if (err) { + mutex_unlock(&hvc_ports_mutex); return ERR_PTR(err); + } } + mutex_unlock(&hvc_ports_mutex); hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size, GFP_KERNEL);