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412f1ad11e
glib2/1357.patch
Michael Catanzaro 412f1ad11e Backport GUnixMountMonitor port to libmnt_monitor 
Make GUnixMountMonitor thread-safe
Resolves: RHEL-23636
2024-02-01 19:35:30 -06:00

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From 8e2854edd33cace8e37167a97b640110d17e9e46 Mon Sep 17 00:00:00 2001
From: Michael Catanzaro <mcatanzaro@redhat.com>
Date: Thu, 1 Feb 2024 18:13:55 -0600
Subject: [PATCH 1/5] Increase availibility of g_unix_mount_get_options()
---
gio/gunixmounts.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gio/gunixmounts.h b/gio/gunixmounts.h
index 72b210dc1..6bef2a323 100644
--- a/gio/gunixmounts.h
+++ b/gio/gunixmounts.h
@@ -81,7 +81,7 @@ GLIB_AVAILABLE_IN_ALL
const char * g_unix_mount_get_device_path (GUnixMountEntry *mount_entry);
GLIB_AVAILABLE_IN_ALL
const char * g_unix_mount_get_fs_type (GUnixMountEntry *mount_entry);
-GLIB_AVAILABLE_IN_2_58
+GLIB_AVAILABLE_IN_2_56
const char * g_unix_mount_get_options (GUnixMountEntry *mount_entry);
GLIB_AVAILABLE_IN_ALL
gboolean g_unix_mount_is_readonly (GUnixMountEntry *mount_entry);
--
2.43.0
From b2bdd8ce2a1af5d5516d9df9564cfd94545ffbfb Mon Sep 17 00:00:00 2001
From: Ondrej Holy <oholy@redhat.com>
Date: Mon, 10 Feb 2020 16:00:42 +0100
Subject: [PATCH 2/5] gunixmounts: Make GUnixMountMonitor thread-safe
The Nautilus test suite often crashes with "GLib-FATAL-CRITICAL:
g_source_is_destroyed: assertion 'g_atomic_int_get (&source->ref_count)
> 0' failed" if it is started with "GIO_USE_VOLUME_MONITOR=unix". This
is because GUnixMountMonitor is simultaneously used from multiple
threads over GLocalFile and GVolumeMonitor APIs. Let's add guards for
proc_mounts_watch_source and mount_poller_time variables to prevent
those crashes.
Fixes: https://gitlab.gnome.org/GNOME/glib/issues/2030
---
gio/gunixmounts.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)
diff --git a/gio/gunixmounts.c b/gio/gunixmounts.c
index 3514e2e8e..a0cd388c4 100644
--- a/gio/gunixmounts.c
+++ b/gio/gunixmounts.c
@@ -151,7 +151,11 @@ static GList *_g_get_unix_mounts (void);
static GList *_g_get_unix_mount_points (void);
static gboolean proc_mounts_watch_is_running (void);
+G_LOCK_DEFINE_STATIC (proc_mounts_source);
+
+/* Protected by proc_mounts_source lock */
static guint64 mount_poller_time = 0;
+static GSource *proc_mounts_watch_source;
#ifdef HAVE_SYS_MNTTAB_H
#define MNTOPT_RO "ro"
@@ -1450,18 +1454,21 @@ get_mounts_timestamp (void)
{
const char *monitor_file;
struct stat buf;
+ guint64 timestamp = 0;
+
+ G_LOCK (proc_mounts_source);
monitor_file = get_mtab_monitor_file ();
/* Don't return mtime for /proc/ files */
if (monitor_file && !g_str_has_prefix (monitor_file, "/proc/"))
{
if (stat (monitor_file, &buf) == 0)
- return (guint64)buf.st_mtime;
+ timestamp = buf.st_mtime;
}
else if (proc_mounts_watch_is_running ())
{
/* it's being monitored by poll, so return mount_poller_time */
- return mount_poller_time;
+ timestamp = mount_poller_time;
}
else
{
@@ -1470,9 +1477,12 @@ get_mounts_timestamp (void)
* return TRUE so any application caches depending on it (like eg.
* the one in GIO) get invalidated and don't hold possibly outdated
* data - see Bug 787731 */
- return (guint64) g_get_monotonic_time ();
+ timestamp = g_get_monotonic_time ();
}
- return 0;
+
+ G_UNLOCK (proc_mounts_source);
+
+ return timestamp;
}
static guint64
@@ -1704,10 +1714,10 @@ G_DEFINE_TYPE (GUnixMountMonitor, g_unix_mount_monitor, G_TYPE_OBJECT)
static GContextSpecificGroup mount_monitor_group;
static GFileMonitor *fstab_monitor;
static GFileMonitor *mtab_monitor;
-static GSource *proc_mounts_watch_source;
static GList *mount_poller_mounts;
static guint mtab_file_changed_id;
+/* Called with proc_mounts_source lock held. */
static gboolean
proc_mounts_watch_is_running (void)
{
@@ -1768,7 +1778,10 @@ proc_mounts_changed (GIOChannel *channel,
{
if (cond & G_IO_ERR)
{
+ G_LOCK (proc_mounts_source);
mount_poller_time = (guint64) g_get_monotonic_time ();
+ G_UNLOCK (proc_mounts_source);
+
g_context_specific_group_emit (&mount_monitor_group, signals[MOUNTS_CHANGED]);
}
@@ -1802,7 +1815,10 @@ mount_change_poller (gpointer user_data)
if (has_changed)
{
+ G_LOCK (proc_mounts_source);
mount_poller_time = (guint64) g_get_monotonic_time ();
+ G_UNLOCK (proc_mounts_source);
+
g_context_specific_group_emit (&mount_monitor_group, signals[MOUNTPOINTS_CHANGED]);
}
@@ -1819,11 +1835,13 @@ mount_monitor_stop (void)
g_object_unref (fstab_monitor);
}
+ G_LOCK (proc_mounts_source);
if (proc_mounts_watch_source != NULL)
{
g_source_destroy (proc_mounts_watch_source);
proc_mounts_watch_source = NULL;
}
+ G_UNLOCK (proc_mounts_source);
if (mtab_monitor)
{
@@ -1869,6 +1887,8 @@ mount_monitor_start (void)
}
else
{
+ G_LOCK (proc_mounts_source);
+
proc_mounts_watch_source = g_io_create_watch (proc_mounts_channel, G_IO_ERR);
g_source_set_callback (proc_mounts_watch_source,
(GSourceFunc) proc_mounts_changed,
@@ -1877,6 +1897,8 @@ mount_monitor_start (void)
g_main_context_get_thread_default ());
g_source_unref (proc_mounts_watch_source);
g_io_channel_unref (proc_mounts_channel);
+
+ G_UNLOCK (proc_mounts_source);
}
}
else
@@ -1889,6 +1911,8 @@ mount_monitor_start (void)
}
else
{
+ G_LOCK (proc_mounts_source);
+
proc_mounts_watch_source = g_timeout_source_new_seconds (3);
mount_poller_mounts = _g_get_unix_mounts ();
mount_poller_time = (guint64)g_get_monotonic_time ();
@@ -1898,6 +1922,8 @@ mount_monitor_start (void)
g_source_attach (proc_mounts_watch_source,
g_main_context_get_thread_default ());
g_source_unref (proc_mounts_watch_source);
+
+ G_UNLOCK (proc_mounts_source);
}
}
--
2.43.0
From 98e7cc97852d148b9ed5276c58470ba59823dd44 Mon Sep 17 00:00:00 2001
From: Ondrej Holy <oholy@redhat.com>
Date: Tue, 18 Feb 2020 09:10:03 +0100
Subject: [PATCH 3/5] gunixmounts: Prevent invalid time_read timestamps
The `get_mounts_timestamp()` function uses `mount_poller_time` when
`proc_mounts_watch_source` is set, but the `mount_poller_time` is not
initialized in the same time as `proc_mounts_watch_source`. This may
cause that zero, or some outdated value is returned. Let's initialize
`mount_poller_time` to prevent invalid values to be returned.
---
gio/gunixmounts.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/gio/gunixmounts.c b/gio/gunixmounts.c
index a0cd388c4..62b256f77 100644
--- a/gio/gunixmounts.c
+++ b/gio/gunixmounts.c
@@ -1890,6 +1890,7 @@ mount_monitor_start (void)
G_LOCK (proc_mounts_source);
proc_mounts_watch_source = g_io_create_watch (proc_mounts_channel, G_IO_ERR);
+ mount_poller_time = (guint64) g_get_monotonic_time ();
g_source_set_callback (proc_mounts_watch_source,
(GSourceFunc) proc_mounts_changed,
NULL, NULL);
--
2.43.0
From e1b9019e3206b9a2dc74c7e587c6367cf33047da Mon Sep 17 00:00:00 2001
From: Ondrej Holy <oholy@redhat.com>
Date: Mon, 17 Feb 2020 11:05:07 +0100
Subject: [PATCH 4/5] gunixmounts: Prevent race when mtab file changed
mtab_file_changed_id might be set on thread default context, but it is
always cleared on the global context because of usage of g_idle_add. This
can cause the emission of redundant "mounts-change" signals. This should
not cause any issues to the client application, but let's attach the idle
source to the thread-default context instead to avoid those races for sure.
---
gio/gunixmounts.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/gio/gunixmounts.c b/gio/gunixmounts.c
index 62b256f77..d01b53c8d 100644
--- a/gio/gunixmounts.c
+++ b/gio/gunixmounts.c
@@ -1756,6 +1756,9 @@ mtab_file_changed (GFileMonitor *monitor,
GFileMonitorEvent event_type,
gpointer user_data)
{
+ GMainContext *context;
+ GSource *source;
+
if (event_type != G_FILE_MONITOR_EVENT_CHANGED &&
event_type != G_FILE_MONITOR_EVENT_CREATED &&
event_type != G_FILE_MONITOR_EVENT_DELETED)
@@ -1768,7 +1771,16 @@ mtab_file_changed (GFileMonitor *monitor,
if (mtab_file_changed_id > 0)
return;
- mtab_file_changed_id = g_idle_add (mtab_file_changed_cb, NULL);
+ context = g_main_context_get_thread_default ();
+ if (!context)
+ context = g_main_context_default ();
+
+ source = g_idle_source_new ();
+ g_source_set_priority (source, G_PRIORITY_DEFAULT);
+ g_source_set_callback (source, mtab_file_changed_cb, NULL, NULL);
+ g_source_set_name (source, "[gio] mtab_file_changed_cb");
+ g_source_attach (source, context);
+ g_source_unref (source);
}
static gboolean
--
2.43.0
From 7dc55e61bd174561851dfaa50fa1420428fb7714 Mon Sep 17 00:00:00 2001
From: Ondrej Holy <oholy@redhat.com>
Date: Mon, 17 Feb 2020 11:20:17 +0100
Subject: [PATCH 5/5] gunixmounts: Remove pending sources when finalizing
mtab_file_changed_id is not currently removed when finalizing, which
could potentially lead to segfaults. Let's remove the source when
finalizing to avoid this.
---
gio/gunixmounts.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/gio/gunixmounts.c b/gio/gunixmounts.c
index d01b53c8d..4695d5618 100644
--- a/gio/gunixmounts.c
+++ b/gio/gunixmounts.c
@@ -1861,6 +1861,12 @@ mount_monitor_stop (void)
g_object_unref (mtab_monitor);
}
+ if (mtab_file_changed_id)
+ {
+ g_source_remove (mtab_file_changed_id);
+ mtab_file_changed_id = 0;
+ }
+
g_list_free_full (mount_poller_mounts, (GDestroyNotify) g_unix_mount_free);
}
--
2.43.0
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