From c56d300086140c93dc3390e5300fd17df802ec0e Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Tue, 28 Jul 2009 00:34:58 +0100 Subject: [PATCH] usb_serial: Fix remaining ref count/lock bugs This fixes - locking bug that was hidden by ecc2e05e739c30870c8e4f252b63a0c4041f2724 - Regression #13821 - Spurious warning when closing and blocking for data write out With these changes my PL2303 always ends up as ttyUSB0 when it should and the module refcounts stay correct. I'll do a more wholesale split & tidy of _open in the next release or two as we get a standard tty_port_open and port->ops->init port->ops->shutdown call backs. Copy sent to Alan Stern and Carlos Mafra just to confirm it fixes all the reports but it passes local testing with the same hardware as Alan Stern. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/usb/serial/usb-serial.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 3c8923f..99188c9 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include "pl2303.h" @@ -184,6 +185,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp) struct usb_serial_port *port; unsigned int portNumber; int retval = 0; + int first = 0; dbg("%s", __func__); @@ -223,7 +225,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp) /* If the console is attached, the device is already open */ if (port->port.count == 1 && !port->console) { - + first = 1; /* lock this module before we call it * this may fail, which means we must bail out, * safe because we are called with BKL held */ @@ -246,13 +248,21 @@ static int serial_open (struct tty_struct *tty, struct file *filp) if (retval) goto bailout_interface_put; mutex_unlock(&serial->disc_mutex); + set_bit(ASYNCB_INITIALIZED, &port->port.flags); } mutex_unlock(&port->mutex); /* Now do the correct tty layer semantics */ retval = tty_port_block_til_ready(&port->port, tty, filp); - if (retval == 0) + if (retval == 0) { + if (!first) + usb_serial_put(serial); return 0; - + } + mutex_lock(&port->mutex); + if (first == 0) + goto bailout_mutex_unlock; + /* Undo the initial port actions */ + mutex_lock(&serial->disc_mutex); bailout_interface_put: usb_autopm_put_interface(serial->interface); bailout_module_put: @@ -411,7 +421,6 @@ static int serial_chars_in_buffer(struct tty_struct *tty) struct usb_serial_port *port = tty->driver_data; dbg("%s = port %d", __func__, port->number); - WARN_ON(!port->port.count); /* if the device was unplugged then any remaining characters fell out of the connector ;) */ if (port->serial->disconnected) -- 2.7.4