Module: xenomai-jki
Branch: for-upstream
Commit: 560d4dcbe2737a5416acf86c9aeb37f59d493fba
URL:
http://git.xenomai.org/?p=xenomai-jki.git;a=commit;h=560d4dcbe2737a5416acf86c9aeb37f59d493fba
Author: Jan Kiszka <jan.kis...@siemens.com>
Date: Fri Aug 20 14:42:07 2010 +0200
RTDM: Plug race between proc_read_dev_info and device deregistration
As the device references passed to proc_read_dev_info may become invalid
while we dereference it, we need to acquire nrt_dev_lock and check the
pointer against our list of registered devices.
Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---
ksrc/skins/rtdm/proc.c | 27 ++++++++++++++++++++++++---
1 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/ksrc/skins/rtdm/proc.c b/ksrc/skins/rtdm/proc.c
index df01b3f..8106ef6 100644
--- a/ksrc/skins/rtdm/proc.c
+++ b/ksrc/skins/rtdm/proc.c
@@ -298,12 +298,32 @@ static struct xnvfile_regular allfd_vfile = {
static int devinfo_vfile_show(struct xnvfile_regular_iterator *it, void *data)
{
- struct rtdm_device *device = xnvfile_priv(it->vfile);
+ struct rtdm_device *device;
+ int i;
+
+ if (down_interruptible(&nrt_dev_lock))
+ return -ERESTARTSYS;
/*
- * Accessing the device during unregister (remove_proc_entry) might be
- * racy, but no official workaround is known yet.
+ * As the device may have disappeared while the handler was called,
+ * first match the pointer against registered devices.
*/
+ for (i = 0; i < devname_hashtab_size; i++)
+ list_for_each_entry(device, &rtdm_named_devices[i],
+ reserved.entry)
+ if (device == xnvfile_priv(it->vfile))
+ goto found;
+
+ for (i = 0; i < protocol_hashtab_size; i++)
+ list_for_each_entry(device, &rtdm_protocol_devices[i],
+ reserved.entry)
+ if (device == xnvfile_priv(it->vfile))
+ goto found;
+
+ up(&nrt_dev_lock);
+ return -ENODEV;
+
+found:
xnvfile_printf(it, "driver:\t\t%s\nversion:\t%d.%d.%d\n",
device->driver_name,
RTDM_DRIVER_MAJOR_VER(device->driver_version),
@@ -327,6 +347,7 @@ static int devinfo_vfile_show(struct
xnvfile_regular_iterator *it, void *data)
xnvfile_printf(it, "lock count:\t%d\n",
atomic_read(&device->reserved.refcount));
+ up(&nrt_dev_lock);
return 0;
}
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