USB: overhaul of mos7840 driver

This fixes:

- breaking DMA rules about buffers
- usage of _global_ variables to save a single device's attributes
- racy access to urb->status
- smp monotonity issue with statistics
- use of one buffer for many simultaneous URBs
- error handling introduced
- several instances of following NULL pointers
- use after free
- unnecessary GFP_ATOMIC
- GFP_KERNEL in interrupt
- various cleanups
- write room granularity issue that bit cdc-acm
- race in shutdown

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 145 insertions, 88 deletions

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index c6cca859af45..2366e7b63ece 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -176,9 +176,12 @@ struct moschip_port {
         int port_num;           /*Actual port number in the device(1,2,etc) */
         struct urb *write_urb;  /* write URB for this port */
         struct urb *read_urb;   /* read URB for this port */
+        struct urb *int_urb;
         __u8 shadowLCR;         /* last LCR value received */
         __u8 shadowMCR;         /* last MCR value received */
         char open;
+        char open_ports;
+        char zombie;
         wait_queue_head_t wait_chase;   /* for handling sleeping while waiting for chase to finish */
         wait_queue_head_t delta_msr_wait;       /* for handling sleeping while waiting for msr change to happen */
         int delta_msr_cond;
@@ -191,17 +194,17 @@ struct moschip_port {
         __u8 DcrRegOffset;
         //for processing control URBS in interrupt context
         struct urb *control_urb;
+        struct usb_ctrlrequest *dr;
         char *ctrl_buf;
         int MsrLsr;
 
+        spinlock_t pool_lock;
         struct urb *write_urb_pool[NUM_URBS];
+        char busy[NUM_URBS];
 };
 
 
 static int debug;
-static int mos7840_num_ports;   //this says the number of ports in the device
-static int mos7840_num_open_ports;
-
 
 /*
  * mos7840_set_reg_sync
@@ -254,7 +257,7 @@ static int mos7840_set_uart_reg(struct usb_serial_port *port, __u16 reg,
         struct usb_device *dev = port->serial->dev;
         val = val & 0x00ff;
         // For the UART control registers, the application number need to be Or'ed
-        if (mos7840_num_ports == 4) {
+        if (port->serial->num_ports == 4) {
                 val |=
                     (((__u16) port->number - (__u16) (port->serial->minor)) +
                      1) << 8;
@@ -294,7 +297,7 @@ static int mos7840_get_uart_reg(struct usb_serial_port *port, __u16 reg,
 
         //dbg("application number is %4x \n",(((__u16)port->number - (__u16)(port->serial->minor))+1)<<8);
         /*Wval  is same as application number */
-        if (mos7840_num_ports == 4) {
+        if (port->serial->num_ports == 4) {
                 Wval =
                     (((__u16) port->number - (__u16) (port->serial->minor)) +
                      1) << 8;
@@ -352,7 +355,7 @@ static inline struct moschip_port *mos7840_get_port_private(struct
         return (struct moschip_port *)usb_get_serial_port_data(port);
 }
 
-static int mos7840_handle_new_msr(struct moschip_port *port, __u8 new_msr)
+static void mos7840_handle_new_msr(struct moschip_port *port, __u8 new_msr)
 {
         struct moschip_port *mos7840_port;
         struct async_icount *icount;
@@ -366,22 +369,24 @@ static int mos7840_handle_new_msr(struct moschip_port *port, __u8 new_msr)
                 /* update input line counters */
                 if (new_msr & MOS_MSR_DELTA_CTS) {
                         icount->cts++;
+                        smp_wmb();
                 }
                 if (new_msr & MOS_MSR_DELTA_DSR) {
                         icount->dsr++;
+                        smp_wmb();
                 }
                 if (new_msr & MOS_MSR_DELTA_CD) {
                         icount->dcd++;
+                        smp_wmb();
                 }
                 if (new_msr & MOS_MSR_DELTA_RI) {
                         icount->rng++;
+                        smp_wmb();
                 }
         }
-
-        return 0;
 }
 
-static int mos7840_handle_new_lsr(struct moschip_port *port, __u8 new_lsr)
+static void mos7840_handle_new_lsr(struct moschip_port *port, __u8 new_lsr)
 {
         struct async_icount *icount;
 
@@ -400,18 +405,20 @@ static int mos7840_handle_new_lsr(struct moschip_port *port, __u8 new_lsr)
         icount = &port->icount;
         if (new_lsr & SERIAL_LSR_BI) {
                 icount->brk++;
+                smp_wmb();
         }
         if (new_lsr & SERIAL_LSR_OE) {
                 icount->overrun++;
+                smp_wmb();
         }
         if (new_lsr & SERIAL_LSR_PE) {
                 icount->parity++;
+                smp_wmb();
         }
         if (new_lsr & SERIAL_LSR_FE) {
                 icount->frame++;
+                smp_wmb();
         }
-
-        return 0;
 }
 
 /************************************************************************/
@@ -426,12 +433,15 @@ static void mos7840_control_callback(struct urb *urb)
         unsigned char *data;
         struct moschip_port *mos7840_port;
         __u8 regval = 0x0;
+        int result = 0;
 
         if (!urb) {
                 dbg("%s", "Invalid Pointer !!!!:\n");
                 return;
         }
 
+        mos7840_port = (struct moschip_port *)urb->context;
+
         switch (urb->status) {
         case 0:
                 /* success */
@@ -449,8 +459,6 @@ static void mos7840_control_callback(struct urb *urb)
                 goto exit;
         }
 
-        mos7840_port = (struct moschip_port *)urb->context;
-
         dbg("%s urb buffer size is %d\n", __FUNCTION__, urb->actual_length);
         dbg("%s mos7840_port->MsrLsr is %d port %d\n", __FUNCTION__,
             mos7840_port->MsrLsr, mos7840_port->port_num);
@@ -462,21 +470,26 @@ static void mos7840_control_callback(struct urb *urb)
         else if (mos7840_port->MsrLsr == 1)
                 mos7840_handle_new_lsr(mos7840_port, regval);
 
-      exit:
-        return;
+exit:
+        spin_lock(&mos7840_port->pool_lock);
+        if (!mos7840_port->zombie)
+                result = usb_submit_urb(mos7840_port->int_urb, GFP_ATOMIC);
+        spin_unlock(&mos7840_port->pool_lock);
+        if (result) {
+                dev_err(&urb->dev->dev,
+                        "%s - Error %d submitting interrupt urb\n",
+                        __FUNCTION__, result);
+        }
 }
 
 static int mos7840_get_reg(struct moschip_port *mcs, __u16 Wval, __u16 reg,
                            __u16 * val)
 {
         struct usb_device *dev = mcs->port->serial->dev;
-        struct usb_ctrlrequest *dr = NULL;
-        unsigned char *buffer = NULL;
-        int ret = 0;
-        buffer = (__u8 *) mcs->ctrl_buf;
+        struct usb_ctrlrequest *dr = mcs->dr;
+        unsigned char *buffer = mcs->ctrl_buf;
+        int ret;
 
-//      dr=(struct usb_ctrlrequest *)(buffer);
-        dr = (void *)(buffer + 2);
         dr->bRequestType = MCS_RD_RTYPE;
         dr->bRequest = MCS_RDREQ;
         dr->wValue = cpu_to_le16(Wval); //0;
@@ -506,8 +519,8 @@ static void mos7840_interrupt_callback(struct urb *urb)
         __u16 Data;
         unsigned char *data;
         __u8 sp[5], st;
-        int i;
-        __u16 wval;
+        int i, rv = 0;
+        __u16 wval, wreg = 0;
 
         dbg("%s", " : Entering\n");
         if (!urb) {
@@ -569,31 +582,34 @@ static void mos7840_interrupt_callback(struct urb *urb)
                                         dbg("Serial Port %d: Receiver status error or ", i);
                                         dbg("address bit detected in 9-bit mode\n");
                                         mos7840_port->MsrLsr = 1;
-                                        mos7840_get_reg(mos7840_port, wval,
-                                                        LINE_STATUS_REGISTER,
-                                                        &Data);
+                                        wreg = LINE_STATUS_REGISTER;
                                         break;
                                 case SERIAL_IIR_MS:
                                         dbg("Serial Port %d: Modem status change\n", i);
                                         mos7840_port->MsrLsr = 0;
-                                        mos7840_get_reg(mos7840_port, wval,
-                                                        MODEM_STATUS_REGISTER,
-                                                        &Data);
+                                        wreg = MODEM_STATUS_REGISTER;
                                         break;
                                 }
+                                spin_lock(&mos7840_port->pool_lock);
+                                if (!mos7840_port->zombie) {
+                                        rv = mos7840_get_reg(mos7840_port, wval, wreg, &Data);
+                                } else {
+                                        spin_unlock(&mos7840_port->pool_lock);
+                                        return;
+                                }
+                                spin_unlock(&mos7840_port->pool_lock);
                         }
                 }
         }
-      exit:
+        if (!(rv < 0)) /* the completion handler for the control urb will resubmit */
+                return;
+exit:
         result = usb_submit_urb(urb, GFP_ATOMIC);
         if (result) {
                 dev_err(&urb->dev->dev,
                         "%s - Error %d submitting interrupt urb\n",
                         __FUNCTION__, result);
         }
-
-        return;
-
 }
 
 static int mos7840_port_paranoia_check(struct usb_serial_port *port,
@@ -634,7 +650,8 @@ static struct usb_serial *mos7840_get_usb_serial(struct usb_serial_port *port,
         if (!port ||
             mos7840_port_paranoia_check(port, function) ||
             mos7840_serial_paranoia_check(port->serial, function)) {
-                /* then say that we don't have a valid usb_serial thing, which will                  * end up genrating -ENODEV return values */
+                /* then say that we don't have a valid usb_serial thing, which will
+                 * end up genrating -ENODEV return values */
                 return NULL;
         }
 
@@ -699,6 +716,7 @@ static void mos7840_bulk_in_callback(struct urb *urb)
                         tty_flip_buffer_push(tty);
                 }
                 mos7840_port->icount.rx += urb->actual_length;
+                smp_wmb();
                 dbg("mos7840_port->icount.rx is %d:\n",
                     mos7840_port->icount.rx);
         }
@@ -708,15 +726,14 @@ static void mos7840_bulk_in_callback(struct urb *urb)
                 return;
         }
 
-        if (mos7840_port->read_urb->status != -EINPROGRESS) {
-                mos7840_port->read_urb->dev = serial->dev;
 
-                status = usb_submit_urb(mos7840_port->read_urb, GFP_ATOMIC);
+        mos7840_port->read_urb->dev = serial->dev;
 
-                if (status) {
-                        dbg(" usb_submit_urb(read bulk) failed, status = %d",
-                            status);
-                }
+        status = usb_submit_urb(mos7840_port->read_urb, GFP_ATOMIC);
+
+        if (status) {
+                dbg(" usb_submit_urb(read bulk) failed, status = %d",
+                 status);
         }
 }
 
@@ -730,17 +747,28 @@ static void mos7840_bulk_out_data_callback(struct urb *urb)
 {
         struct moschip_port *mos7840_port;
         struct tty_struct *tty;
+        int i;
+
         if (!urb) {
                 dbg("%s", "Invalid Pointer !!!!:\n");
                 return;
         }
 
+        mos7840_port = (struct moschip_port *)urb->context;
+        spin_lock(&mos7840_port->pool_lock);
+        for (i = 0; i < NUM_URBS; i++) {
+                if (urb == mos7840_port->write_urb_pool[i]) {
+                        mos7840_port->busy[i] = 0;
+                        break;
+                }
+        }
+        spin_unlock(&mos7840_port->pool_lock);
+
         if (urb->status) {
                 dbg("nonzero write bulk status received:%d\n", urb->status);
                 return;
         }
 
-        mos7840_port = (struct moschip_port *)urb->context;
         if (!mos7840_port) {
                 dbg("%s", "NULL mos7840_port pointer \n");
                 return;
@@ -792,13 +820,13 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         __u16 Data;
         int status;
         struct moschip_port *mos7840_port;
+        struct moschip_port *port0;
 
         if (mos7840_port_paranoia_check(port, __FUNCTION__)) {
                 dbg("%s", "Port Paranoia failed \n");
                 return -ENODEV;
         }
 
-        mos7840_num_open_ports++;
         serial = port->serial;
 
         if (mos7840_serial_paranoia_check(serial, __FUNCTION__)) {
@@ -807,16 +835,18 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         }
 
         mos7840_port = mos7840_get_port_private(port);
+        port0 = mos7840_get_port_private(serial->port[0]);
 
-        if (mos7840_port == NULL)
+        if (mos7840_port == NULL || port0 == NULL)
                 return -ENODEV;
 
         usb_clear_halt(serial->dev, port->write_urb->pipe);
         usb_clear_halt(serial->dev, port->read_urb->pipe);
+        port0->open_ports++;
 
         /* Initialising the write urb pool */
         for (j = 0; j < NUM_URBS; ++j) {
-                urb = usb_alloc_urb(0, GFP_ATOMIC);
+                urb = usb_alloc_urb(0, GFP_KERNEL);
                 mos7840_port->write_urb_pool[j] = urb;
 
                 if (urb == NULL) {
@@ -824,10 +854,10 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
                         continue;
                 }
 
-                urb->transfer_buffer = NULL;
-                urb->transfer_buffer =
-                    kmalloc(URB_TRANSFER_BUFFER_SIZE, GFP_KERNEL);
+                urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE, GFP_KERNEL);
                 if (!urb->transfer_buffer) {
+                        usb_free_urb(urb);
+                        mos7840_port->write_urb_pool[j] = NULL;
                         err("%s-out of memory for urb buffers.", __FUNCTION__);
                         continue;
                 }
@@ -879,9 +909,7 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         }
         Data |= 0x08;           //Driver done bit
         Data |= 0x20;           //rx_disable
-        status = 0;
-        status =
-            mos7840_set_reg_sync(port, mos7840_port->ControlRegOffset, Data);
+        status = mos7840_set_reg_sync(port, mos7840_port->ControlRegOffset, Data);
         if (status < 0) {
                 dbg("writing Controlreg failed\n");
                 return -1;
@@ -893,7 +921,6 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         ////////////////////////////////////
 
         Data = 0x00;
-        status = 0;
         status = mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);
         if (status < 0) {
                 dbg("disableing interrupts failed\n");
@@ -901,7 +928,6 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         }
         // Set FIFO_CONTROL_REGISTER to the default value
         Data = 0x00;
-        status = 0;
         status = mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);
         if (status < 0) {
                 dbg("Writing FIFO_CONTROL_REGISTER  failed\n");
@@ -909,7 +935,6 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         }
 
         Data = 0xcf;
-        status = 0;
         status = mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);
         if (status < 0) {
                 dbg("Writing FIFO_CONTROL_REGISTER  failed\n");
@@ -917,22 +942,18 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
         }
 
         Data = 0x03;
-        status = 0;
         status = mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);
         mos7840_port->shadowLCR = Data;
 
         Data = 0x0b;
-        status = 0;
         status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);
         mos7840_port->shadowMCR = Data;
 
         Data = 0x00;
-        status = 0;
         status = mos7840_get_uart_reg(port, LINE_CONTROL_REGISTER, &Data);
         mos7840_port->shadowLCR = Data;
 
         Data |= SERIAL_LCR_DLAB;        //data latch enable in LCR 0x80
-        status = 0;
         status = mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);
 
         Data = 0x0c;
@@ -999,7 +1020,7 @@ static int mos7840_open(struct usb_serial_port *port, struct file *filp)
 /* Check to see if we've set up our endpoint info yet    *
      * (can't set it up in mos7840_startup as the structures *
      * were not set up at that time.)                        */
-        if (mos7840_num_open_ports == 1) {
+        if (port0->open_ports == 1) {
                 if (serial->port[0]->interrupt_in_buffer == NULL) {
 
                         /* set up interrupt urb */
@@ -1097,6 +1118,7 @@ static int mos7840_chars_in_buffer(struct usb_serial_port *port)
 {
         int i;
         int chars = 0;
+        unsigned long flags;
         struct moschip_port *mos7840_port;
 
         dbg("%s \n", " mos7840_chars_in_buffer:entering ...........");
@@ -1112,13 +1134,15 @@ static int mos7840_chars_in_buffer(struct usb_serial_port *port)
                 return -1;
         }
 
+        spin_lock_irqsave(&mos7840_port->pool_lock,flags);
         for (i = 0; i < NUM_URBS; ++i) {
-                if (mos7840_port->write_urb_pool[i]->status == -EINPROGRESS) {
+                if (mos7840_port->busy[i]) {
                         chars += URB_TRANSFER_BUFFER_SIZE;
                 }
         }
+        spin_unlock_irqrestore(&mos7840_port->pool_lock,flags);
         dbg("%s - returns %d", __FUNCTION__, chars);
-        return (chars);
+        return chars;
 
 }
 
@@ -1172,6 +1196,7 @@ static void mos7840_close(struct usb_serial_port *port, struct file *filp)
 {
         struct usb_serial *serial;
         struct moschip_port *mos7840_port;
+        struct moschip_port *port0;
         int j;
         __u16 Data;
 
@@ -1189,10 +1214,10 @@ static void mos7840_close(struct usb_serial_port *port, struct file *filp)
         }
 
         mos7840_port = mos7840_get_port_private(port);
+        port0 = mos7840_get_port_private(serial->port[0]);
 
-        if (mos7840_port == NULL) {
+        if (mos7840_port == NULL || port0 == NULL)
                 return;
-        }
 
         for (j = 0; j < NUM_URBS; ++j)
                 usb_kill_urb(mos7840_port->write_urb_pool[j]);
@@ -1234,12 +1259,13 @@ static void mos7840_close(struct usb_serial_port *port, struct file *filp)
         }
 //              if(mos7840_port->ctrl_buf != NULL)
 //                      kfree(mos7840_port->ctrl_buf);
-        mos7840_num_open_ports--;
+        port0->open_ports--;
         dbg("mos7840_num_open_ports in close%d:in port%d\n",
-            mos7840_num_open_ports, port->number);
-        if (mos7840_num_open_ports == 0) {
+            port0->open_ports, port->number);
+        if (port0->open_ports == 0) {
                 if (serial->port[0]->interrupt_in_urb) {
                         dbg("%s", "Shutdown interrupt_in_urb\n");
+                        usb_kill_urb(serial->port[0]->interrupt_in_urb);
                 }
         }
 
@@ -1368,6 +1394,7 @@ static int mos7840_write_room(struct usb_serial_port *port)
 {
         int i;
         int room = 0;
+        unsigned long flags;
         struct moschip_port *mos7840_port;
 
         dbg("%s \n", " mos7840_write_room:entering ...........");
@@ -1384,14 +1411,17 @@ static int mos7840_write_room(struct usb_serial_port *port)
                 return -1;
         }
 
+        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
         for (i = 0; i < NUM_URBS; ++i) {
-                if (mos7840_port->write_urb_pool[i]->status != -EINPROGRESS) {
+                if (!mos7840_port->busy[i]) {
                         room += URB_TRANSFER_BUFFER_SIZE;
                 }
         }
+        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);
 
+        room = (room == 0) ? 0 : room - URB_TRANSFER_BUFFER_SIZE + 1;
         dbg("%s - returns %d", __FUNCTION__, room);
-        return (room);
+        return room;
 
 }
 
@@ -1410,6 +1440,7 @@ static int mos7840_write(struct usb_serial_port *port,
         int i;
         int bytes_sent = 0;
         int transfer_size;
+        unsigned long flags;
 
         struct moschip_port *mos7840_port;
         struct usb_serial *serial;
@@ -1476,13 +1507,16 @@ static int mos7840_write(struct usb_serial_port *port,
         /* try to find a free urb in the list */
         urb = NULL;
 
+        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
         for (i = 0; i < NUM_URBS; ++i) {
-                if (mos7840_port->write_urb_pool[i]->status != -EINPROGRESS) {
+                if (!mos7840_port->busy[i]) {
+                        mos7840_port->busy[i] = 1;
                         urb = mos7840_port->write_urb_pool[i];
                         dbg("\nURB:%d", i);
                         break;
                 }
         }
+        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);
 
         if (urb == NULL) {
                 dbg("%s - no more free urbs", __FUNCTION__);
@@ -1518,6 +1552,7 @@ static int mos7840_write(struct usb_serial_port *port,
         status = usb_submit_urb(urb, GFP_ATOMIC);
 
         if (status) {
+                mos7840_port->busy[i] = 0;
                 err("%s - usb_submit_urb(write bulk) failed with status = %d",
                     __FUNCTION__, status);
                 bytes_sent = status;
@@ -1525,6 +1560,7 @@ static int mos7840_write(struct usb_serial_port *port,
         }
         bytes_sent = transfer_size;
         mos7840_port->icount.tx += transfer_size;
+        smp_wmb();
         dbg("mos7840_port->icount.tx is %d:\n", mos7840_port->icount.tx);
       exit:
 
@@ -2490,6 +2526,7 @@ static int mos7840_ioctl(struct usb_serial_port *port, struct file *file,
                         if (signal_pending(current))
                                 return -ERESTARTSYS;
                         cnow = mos7840_port->icount;
+                        smp_rmb();
                         if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
                             cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
                                 return -EIO;    /* no change => error */
@@ -2506,6 +2543,7 @@ static int mos7840_ioctl(struct usb_serial_port *port, struct file *file,
 
         case TIOCGICOUNT:
                 cnow = mos7840_port->icount;
+                smp_rmb();
                 icount.cts = cnow.cts;
                 icount.dsr = cnow.dsr;
                 icount.rng = cnow.rng;
@@ -2535,19 +2573,18 @@ static int mos7840_ioctl(struct usb_serial_port *port, struct file *file,
 
 static int mos7840_calc_num_ports(struct usb_serial *serial)
 {
+        int mos7840_num_ports = 0;
 
         dbg("numberofendpoints: %d \n",
             (int)serial->interface->cur_altsetting->desc.bNumEndpoints);
         dbg("numberofendpoints: %d \n",
             (int)serial->interface->altsetting->desc.bNumEndpoints);
         if (serial->interface->cur_altsetting->desc.bNumEndpoints == 5) {
-                mos7840_num_ports = 2;
-                serial->type->num_ports = 2;
+                mos7840_num_ports = serial->num_ports = 2;
         } else if (serial->interface->cur_altsetting->desc.bNumEndpoints == 9) {
-                mos7840_num_ports = 4;
-                serial->type->num_bulk_in = 4;
-                serial->type->num_bulk_out = 4;
-                serial->type->num_ports = 4;
+                serial->num_bulk_in = 4;
+                serial->num_bulk_out = 4;
+                mos7840_num_ports = serial->num_ports = 4;
         }
 
         return mos7840_num_ports;
@@ -2583,7 +2620,9 @@ static int mos7840_startup(struct usb_serial *serial)
                 mos7840_port = kzalloc(sizeof(struct moschip_port), GFP_KERNEL);
                 if (mos7840_port == NULL) {
                         err("%s - Out of memory", __FUNCTION__);
-                        return -ENOMEM;
+                        status = -ENOMEM;
+                        i--; /* don't follow NULL pointer cleaning up */
+                        goto error;
                 }
 
                 /* Initialize all port interrupt end point to port 0 int endpoint *
@@ -2591,6 +2630,7 @@ static int mos7840_startup(struct usb_serial *serial)
 
                 mos7840_port->port = serial->port[i];
                 mos7840_set_port_private(serial->port[i], mos7840_port);
+                spin_lock_init(&mos7840_port->pool_lock);
 
                 mos7840_port->port_num = ((serial->port[i]->number -
                                            (serial->port[i]->serial->minor)) +
@@ -2601,22 +2641,22 @@ static int mos7840_startup(struct usb_serial *serial)
                         mos7840_port->ControlRegOffset = 0x1;
                         mos7840_port->DcrRegOffset = 0x4;
                 } else if ((mos7840_port->port_num == 2)
-                           && (mos7840_num_ports == 4)) {
+                           && (serial->num_ports == 4)) {
                         mos7840_port->SpRegOffset = 0x8;
                         mos7840_port->ControlRegOffset = 0x9;
                         mos7840_port->DcrRegOffset = 0x16;
                 } else if ((mos7840_port->port_num == 2)
-                           && (mos7840_num_ports == 2)) {
+                           && (serial->num_ports == 2)) {
                         mos7840_port->SpRegOffset = 0xa;
                         mos7840_port->ControlRegOffset = 0xb;
                         mos7840_port->DcrRegOffset = 0x19;
                 } else if ((mos7840_port->port_num == 3)
-                           && (mos7840_num_ports == 4)) {
+                           && (serial->num_ports == 4)) {
                         mos7840_port->SpRegOffset = 0xa;
                         mos7840_port->ControlRegOffset = 0xb;
                         mos7840_port->DcrRegOffset = 0x19;
                 } else if ((mos7840_port->port_num == 4)
-                           && (mos7840_num_ports == 4)) {
+                           && (serial->num_ports == 4)) {
                         mos7840_port->SpRegOffset = 0xc;
                         mos7840_port->ControlRegOffset = 0xd;
                         mos7840_port->DcrRegOffset = 0x1c;
@@ -2701,21 +2741,19 @@ static int mos7840_startup(struct usb_serial *serial)
                         dbg("CLK_START_VALUE_REGISTER Writing success status%d\n", status);
 
                 Data = 0x20;
-                status = 0;
                 status =
                     mos7840_set_reg_sync(serial->port[i], CLK_MULTI_REGISTER,
                                          Data);
                 if (status < 0) {
                         dbg("Writing CLK_MULTI_REGISTER failed status-0x%x\n",
                             status);
-                        break;
+                        goto error;
                 } else
                         dbg("CLK_MULTI_REGISTER Writing success status%d\n",
                             status);
 
                 //write value 0x0 to scratchpad register
                 Data = 0x00;
-                status = 0;
                 status =
                     mos7840_set_uart_reg(serial->port[i], SCRATCH_PAD_REGISTER,
                                          Data);
@@ -2729,7 +2767,7 @@ static int mos7840_startup(struct usb_serial *serial)
 
                 //Zero Length flag register
                 if ((mos7840_port->port_num != 1)
-                    && (mos7840_num_ports == 2)) {
+                    && (serial->num_ports == 2)) {
 
                         Data = 0xff;
                         status = 0;
@@ -2770,14 +2808,17 @@ static int mos7840_startup(struct usb_serial *serial)
                                     i + 1, status);
 
                 }
-                mos7840_port->control_urb = usb_alloc_urb(0, GFP_ATOMIC);
+                mos7840_port->control_urb = usb_alloc_urb(0, GFP_KERNEL);
                 mos7840_port->ctrl_buf = kmalloc(16, GFP_KERNEL);
-
+                mos7840_port->dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
+                if (!mos7840_port->control_urb || !mos7840_port->ctrl_buf || !mos7840_port->dr) {
+                        status = -ENOMEM;
+                        goto error;
+                }
         }
 
         //Zero Length flag enable
         Data = 0x0f;
-        status = 0;
         status = mos7840_set_reg_sync(serial->port[0], ZLP_REG5, Data);
         if (status < 0) {
                 dbg("Writing ZLP_REG5 failed status-0x%x\n", status);
@@ -2789,6 +2830,17 @@ static int mos7840_startup(struct usb_serial *serial)
         usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                         (__u8) 0x03, 0x00, 0x01, 0x00, NULL, 0x00, 5 * HZ);
         return 0;
+error:
+        for (/* nothing */; i >= 0; i--) {
+                mos7840_port = mos7840_get_port_private(serial->port[i]);
+
+                kfree(mos7840_port->dr);
+                kfree(mos7840_port->ctrl_buf);
+                usb_free_urb(mos7840_port->control_urb);
+                kfree(mos7840_port);
+                serial->port[i] = NULL;
+        }
+        return status;
 }
 
 /****************************************************************************
@@ -2799,6 +2851,7 @@ static int mos7840_startup(struct usb_serial *serial)
 static void mos7840_shutdown(struct usb_serial *serial)
 {
         int i;
+        unsigned long flags;
         struct moschip_port *mos7840_port;
         dbg("%s \n", " shutdown :entering..........");
 
@@ -2814,8 +2867,12 @@ static void mos7840_shutdown(struct usb_serial *serial)
 
         for (i = 0; i < serial->num_ports; ++i) {
                 mos7840_port = mos7840_get_port_private(serial->port[i]);
-                kfree(mos7840_port->ctrl_buf);
+                spin_lock_irqsave(&mos7840_port->pool_lock, flags);
+                mos7840_port->zombie = 1;
+                spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);
                 usb_kill_urb(mos7840_port->control_urb);
+                kfree(mos7840_port->ctrl_buf);
+                kfree(mos7840_port->dr);
                 kfree(mos7840_port);
                 mos7840_set_port_private(serial->port[i], NULL);
         }