From: Peter Hurley Date: Thu, 16 Oct 2014 20:54:19 +0000 (-0400) Subject: serial: core: Flush ldisc after dropping port mutex in uart_close() X-Git-Tag: omap-for-v3.19/fixes-rc1~86^2~166 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2e758910832dce99761a29688b33fd77dcbf6f6c;p=pandora-kernel.git serial: core: Flush ldisc after dropping port mutex in uart_close() The tty buffers (and any line discipline buffers) must be flushed after the UART hardware has shutdown; otherwise, a racing open on the same tty may receive data from the previous session, which is a security hazard. However, holding the port mutex while flushing the line discipline buffers creates a lock inversion if the set_termios() handler takes the port mutex (as it does in the followup patch, 'serial: Fix locking for uart driver set_termios method'. Flush the ldisc buffers after dropping the port mutex; the tty lock is still held which prevents a concurrent open() from advancing while flushing. Since no new rx data is possible after uart_shutdown() until a new open reinitializes the port, the later flush has no impact on what data is being discarded. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed