Return-Path: Date: Wed, 30 May 2012 21:32:27 +0300 From: Ido Yariv To: Johan Hedberg Cc: linux-bluetooth@vger.kernel.org Subject: Re: [PATCH] attrib-server: Fix multiple channels detaching mix-up Message-ID: <20120530183227.GA16709@WorkStation.localnet> References: <1338322808-15503-1-git-send-email-ido@wizery.com> <20120530073701.GB6539@x220> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20120530073701.GB6539@x220> Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Johan, On Wed, May 30, 2012 at 10:37:01AM +0300, Johan Hedberg wrote: > Hi Ido, > > On Tue, May 29, 2012, Ido Yariv wrote: > > The identifier returned by g_attrib_register is not unique across > > different channels. Since attrib_channel_detach assumes this identifier > > to be unique, it may end up detaching the wrong channel when a device > > disconnects. > > > > Fix this by using the channel's pointer as a unique identifier for > > detaching the channel. The identifier returned from g_attrib_register > > will still be used to find the relevant event structure. > > --- > > src/attrib-server.c | 22 +++++++--------------- > > 1 files changed, 7 insertions(+), 15 deletions(-) > > > > diff --git a/src/attrib-server.c b/src/attrib-server.c > > index dd1bba4..39085de 100644 > > --- a/src/attrib-server.c > > +++ b/src/attrib-server.c > > @@ -72,7 +72,7 @@ struct gatt_channel { > > GAttrib *attrib; > > guint mtu; > > gboolean le; > > - guint id; > > + guint event_id; > > gboolean encrypted; > > struct gatt_server *server; > > guint cleanup_id; > > @@ -1077,8 +1077,8 @@ guint attrib_channel_attach(GAttrib *attrib) > > > > > > channel->attrib = g_attrib_ref(attrib); > > - channel->id = g_attrib_register(channel->attrib, GATTRIB_ALL_REQS, > > - channel_handler, channel, NULL); > > + channel->event_id = g_attrib_register(channel->attrib, GATTRIB_ALL_REQS, > > + channel_handler, channel, NULL); > > > > channel->cleanup_id = g_io_add_watch(io, G_IO_HUP, channel_watch_cb, > > channel); > > @@ -1087,15 +1087,7 @@ guint attrib_channel_attach(GAttrib *attrib) > > > > server->clients = g_slist_append(server->clients, channel); > > > > - return channel->id; > > -} > > - > > -static gint channel_id_cmp(gconstpointer data, gconstpointer user_data) > > -{ > > - const struct gatt_channel *channel = data; > > - guint id = GPOINTER_TO_UINT(user_data); > > - > > - return channel->id - id; > > + return GPOINTER_TO_UINT(channel); > > I don't think converting a pointer to uint is safe since some systems > can have 64-bit pointers but 32-bit uints. These macros are therefore > only safe to be used in the other direction, i.e. when starting off with > an uint and passing it to an API that expects a pointer. You're absolutely right, good catch! How about the below patch? Instead of casting to and from guint, we can simply work with gpointer instead. Thanks, Ido. >From 78254bb099f80ad38e10075fbb73a4d990217630 Mon Sep 17 00:00:00 2001 From: Ido Yariv Date: Tue, 29 May 2012 21:11:16 +0300 Subject: [PATCH v2] attrib-server: Fix multiple channels detaching mix-up The identifier returned by g_attrib_register is not unique across different channels. Since attrib_channel_detach assumes this identifier to be unique, it may end up detaching the wrong channel when a device disconnects. Fix this by using the channel's pointer as a unique identifier for detaching the channel. The identifier returned from g_attrib_register will still be used to find the relevant event structure. --- src/attrib-server.c | 26 +++++++++----------------- src/attrib-server.h | 4 ++-- src/device.c | 6 +++--- 3 files changed, 14 insertions(+), 22 deletions(-) diff --git a/src/attrib-server.c b/src/attrib-server.c index a6262d0..db2c52d 100644 --- a/src/attrib-server.c +++ b/src/attrib-server.c @@ -73,7 +73,7 @@ struct gatt_channel { GAttrib *attrib; guint mtu; gboolean le; - guint id; + guint event_id; gboolean encrypted; struct gatt_server *server; guint cleanup_id; @@ -1023,7 +1023,7 @@ done: NULL, NULL, NULL); } -guint attrib_channel_attach(GAttrib *attrib) +gpointer attrib_channel_attach(GAttrib *attrib) { struct gatt_server *server; struct btd_device *device; @@ -1078,8 +1078,8 @@ guint attrib_channel_attach(GAttrib *attrib) channel->attrib = g_attrib_ref(attrib); - channel->id = g_attrib_register(channel->attrib, GATTRIB_ALL_REQS, - channel_handler, channel, NULL); + channel->event_id = g_attrib_register(channel->attrib, GATTRIB_ALL_REQS, + channel_handler, channel, NULL); channel->cleanup_id = g_io_add_watch(io, G_IO_HUP, channel_watch_cb, channel); @@ -1088,18 +1088,10 @@ guint attrib_channel_attach(GAttrib *attrib) server->clients = g_slist_append(server->clients, channel); - return channel->id; + return (gpointer)channel; } -static gint channel_id_cmp(gconstpointer data, gconstpointer user_data) -{ - const struct gatt_channel *channel = data; - guint id = GPOINTER_TO_UINT(user_data); - - return channel->id - id; -} - -gboolean attrib_channel_detach(GAttrib *attrib, guint id) +gboolean attrib_channel_detach(GAttrib *attrib, gpointer id) { struct gatt_server *server; struct gatt_channel *channel; @@ -1123,14 +1115,14 @@ gboolean attrib_channel_detach(GAttrib *attrib, guint id) if (server == NULL) return FALSE; - l = g_slist_find_custom(server->clients, GUINT_TO_POINTER(id), - channel_id_cmp); + /* Make sure the channel was not already freed */ + l = g_slist_find(server->clients, id); if (!l) return FALSE; channel = l->data; - g_attrib_unregister(channel->attrib, channel->id); + g_attrib_unregister(channel->attrib, channel->event_id); channel_remove(channel); return TRUE; diff --git a/src/attrib-server.h b/src/attrib-server.h index 7af0cfa..895d9ef 100644 --- a/src/attrib-server.h +++ b/src/attrib-server.h @@ -36,5 +36,5 @@ int attrib_gap_set(struct btd_adapter *adapter, uint16_t uuid, uint32_t attrib_create_sdp(struct btd_adapter *adapter, uint16_t handle, const char *name); void attrib_free_sdp(uint32_t sdp_handle); -guint attrib_channel_attach(GAttrib *attrib); -gboolean attrib_channel_detach(GAttrib *attrib, guint id); +gpointer attrib_channel_attach(GAttrib *attrib); +gboolean attrib_channel_detach(GAttrib *attrib, gpointer id); diff --git a/src/device.c b/src/device.c index 7ff09aa..543055f 100644 --- a/src/device.c +++ b/src/device.c @@ -154,7 +154,7 @@ struct btd_device { GAttrib *attrib; GSList *attios; GSList *attios_offline; - guint attachid; /* Attrib server attach */ + gpointer attachid; /* Attrib server attach */ guint auto_id; /* Auto connect source id */ gboolean connected; @@ -205,7 +205,7 @@ static void att_cleanup(struct btd_device *device) { if (device->attachid) { attrib_channel_detach(device->attrib, device->attachid); - device->attachid = 0; + device->attachid = NULL; } if (device->cleanup_id) { @@ -1944,7 +1944,7 @@ static void att_connect_cb(GIOChannel *io, GError *gerr, gpointer user_data) attrib = g_attrib_new(io); device->attachid = attrib_channel_attach(attrib); - if (device->attachid == 0) + if (device->attachid == NULL) error("Attribute server attach failure!"); device->attrib = attrib; -- 1.7.7.6