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commit 9de2c43acf37a17dc4c69ff78bb099b80fb74325 upstream. Apparently an application that opens a device and calls select() on it, will hang if the decice is disconnected. It's a little surprising that we had this bug for 15 years, but apparently nobody ever uses select() with a printer: only write() and read(), and those work fine. Well, you can also select() with a timeout. The fix is modeled after devio.c. A few other drivers check the condition first, then do not add the wait queue in case the device is disconnected. We doubt that's completely race-free. So, this patch adds the process first, then locks properly and checks for the disconnect. Reviewed-by: Zqiang <qiang.zhang@windriver.com> Signed-off-by: Pete Zaitcev <zaitcev@redhat.com> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20210303221053.1cf3313e@suzdal.zaitcev.lan Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| cdc-acm.c | ||
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| usbtmc.c | ||