diff options
Diffstat (limited to 'core/libusbx/0001-linux-Use-a-separate-lock-to-serialize-start-stop-vs.patch')
-rw-r--r-- | core/libusbx/0001-linux-Use-a-separate-lock-to-serialize-start-stop-vs.patch | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/core/libusbx/0001-linux-Use-a-separate-lock-to-serialize-start-stop-vs.patch b/core/libusbx/0001-linux-Use-a-separate-lock-to-serialize-start-stop-vs.patch new file mode 100644 index 000000000..b66abd48f --- /dev/null +++ b/core/libusbx/0001-linux-Use-a-separate-lock-to-serialize-start-stop-vs.patch @@ -0,0 +1,103 @@ +From daf4c9fadaf8a49198c53c039bf78980dc251a4b Mon Sep 17 00:00:00 2001 +From: Hans de Goede <hdegoede@redhat.com> +Date: Tue, 30 Jul 2013 15:57:16 +0200 +Subject: [PATCH 1/2] linux: Use a separate lock to serialize start/stop vs + hotplug events + +Using one lock for this is a bad idea, as we should not be holding any +locks used by the hotplug thread when trying to stop otherwise the stop +function may wait indefinetely in pthread_join, while the event-thread +is waiting for the lock the caller of the stop function holds. + +Using 2 separate locks for this should fix this deadlock, which has been +reported here: https://bugzilla.redhat.com/show_bug.cgi?id=985484 + +Many thanks to Chris Dickens for figuring out the cause of this deadlock! + +CC: Chris Dickens <christopher.a.dickens@gmail.com> +Signed-off-by: Hans de Goede <hdegoede@redhat.com> +--- + libusb/os/linux_usbfs.c | 24 +++++++++++++++++------- + libusb/version_nano.h | 2 +- + 2 files changed, 18 insertions(+), 8 deletions(-) + +diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c +index 09288af..90e23b7 100644 +--- a/libusb/os/linux_usbfs.c ++++ b/libusb/os/linux_usbfs.c +@@ -120,7 +120,9 @@ static int sysfs_has_descriptors = -1; + /* how many times have we initted (and not exited) ? */ + static volatile int init_count = 0; + +-/* Serialize hotplug start/stop, scan-devices, event-thread, and poll */ ++/* Serialize hotplug start/stop */ ++usbi_mutex_static_t linux_hotplug_startstop_lock = USBI_MUTEX_INITIALIZER; ++/* Serialize scan-devices, event-thread, and poll */ + usbi_mutex_static_t linux_hotplug_lock = USBI_MUTEX_INITIALIZER; + + static int linux_start_event_monitor(void); +@@ -419,7 +421,7 @@ static int op_init(struct libusb_context *ctx) + if (sysfs_has_descriptors) + usbi_dbg("sysfs has complete descriptors"); + +- usbi_mutex_static_lock(&linux_hotplug_lock); ++ usbi_mutex_static_lock(&linux_hotplug_startstop_lock); + r = LIBUSB_SUCCESS; + if (init_count == 0) { + /* start up hotplug event handler */ +@@ -433,20 +435,20 @@ static int op_init(struct libusb_context *ctx) + linux_stop_event_monitor(); + } else + usbi_err(ctx, "error starting hotplug event monitor"); +- usbi_mutex_static_unlock(&linux_hotplug_lock); ++ usbi_mutex_static_unlock(&linux_hotplug_startstop_lock); + + return r; + } + + static void op_exit(void) + { +- usbi_mutex_static_lock(&linux_hotplug_lock); ++ usbi_mutex_static_lock(&linux_hotplug_startstop_lock); + assert(init_count != 0); + if (!--init_count) { + /* tear down event handler */ + (void)linux_stop_event_monitor(); + } +- usbi_mutex_static_unlock(&linux_hotplug_lock); ++ usbi_mutex_static_unlock(&linux_hotplug_startstop_lock); + } + + static int linux_start_event_monitor(void) +@@ -469,11 +471,19 @@ static int linux_stop_event_monitor(void) + + static int linux_scan_devices(struct libusb_context *ctx) + { ++ int ret; ++ ++ usbi_mutex_static_lock(&linux_hotplug_lock); ++ + #if defined(USE_UDEV) +- return linux_udev_scan_devices(ctx); ++ ret = linux_udev_scan_devices(ctx); + #else +- return linux_default_scan_devices(ctx); ++ ret = linux_default_scan_devices(ctx); + #endif ++ ++ usbi_mutex_static_unlock(&linux_hotplug_lock); ++ ++ return ret; + } + + static void op_hotplug_poll(void) +diff --git a/libusb/version_nano.h b/libusb/version_nano.h +index ebf41e1..34e26ff 100644 +--- a/libusb/version_nano.h ++++ b/libusb/version_nano.h +@@ -1 +1 @@ +-#define LIBUSB_NANO 10774 ++#define LIBUSB_NANO 10777 +-- +1.8.3.1 + |