[PATCH] DVB: Fix locking problems and code cleanup

Fix locking problems and code cleanup

Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.net>
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 46 deletions

diff --git a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
index 2aa767f9bd7d..cb2e7d6ba283 100644
--- a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
+++ b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
@@ -35,7 +35,7 @@
 #include <linux/moduleparam.h>
 #include <linux/vmalloc.h>
 #include <linux/delay.h>
-#include <linux/rwsem.h>
+#include <linux/spinlock.h>
 #include <linux/sched.h>
 
 #include "dvb_ca_en50221.h"
@@ -111,9 +111,6 @@ struct dvb_ca_slot {
         /* size of the buffer to use when talking to the CAM */
         int link_buf_size;
 
-        /* semaphore for syncing access to slot structure */
-        struct rw_semaphore sem;
-
         /* buffer for incoming packets */
         struct dvb_ringbuffer rx_buffer;
 
@@ -602,14 +599,11 @@ static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, u8 * eb
         if (ebuf == NULL) {
                 int buf_free;
 
-                down_read(&ca->slot_info[slot].sem);
                 if (ca->slot_info[slot].rx_buffer.data == NULL) {
-                        up_read(&ca->slot_info[slot].sem);
                         status = -EIO;
                         goto exit;
                 }
                 buf_free = dvb_ringbuffer_free(&ca->slot_info[slot].rx_buffer);
-                up_read(&ca->slot_info[slot].sem);
 
                 if (buf_free < (ca->slot_info[slot].link_buf_size + DVB_RINGBUFFER_PKTHDRSIZE)) {
                         status = -EAGAIN;
@@ -680,14 +674,11 @@ static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, u8 * eb
 
         /* OK, add it to the receive buffer, or copy into external buffer if supplied */
         if (ebuf == NULL) {
-                down_read(&ca->slot_info[slot].sem);
                 if (ca->slot_info[slot].rx_buffer.data == NULL) {
-                        up_read(&ca->slot_info[slot].sem);
                         status = -EIO;
                         goto exit;
                 }
                 dvb_ringbuffer_pkt_write(&ca->slot_info[slot].rx_buffer, buf, bytes_read);
-                up_read(&ca->slot_info[slot].sem);
         } else {
                 memcpy(ebuf, buf, bytes_read);
         }
@@ -802,12 +793,8 @@ static int dvb_ca_en50221_slot_shutdown(struct dvb_ca_private *ca, int slot)
 {
         dprintk("%s\n", __FUNCTION__);
 
-        down_write(&ca->slot_info[slot].sem);
         ca->pub->slot_shutdown(ca->pub, slot);
         ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_NONE;
-        vfree(ca->slot_info[slot].rx_buffer.data);
-        ca->slot_info[slot].rx_buffer.data = NULL;
-        up_write(&ca->slot_info[slot].sem);
 
         /* need to wake up all processes to check if they're now
            trying to write to a defunct CAM */
@@ -893,7 +880,7 @@ void dvb_ca_en50221_frda_irq(struct dvb_ca_en50221 *pubca, int slot)
 
         case DVB_CA_SLOTSTATE_RUNNING:
                 if (ca->open)
-                        dvb_ca_en50221_read_data(ca, slot, NULL, 0);
+                        dvb_ca_en50221_thread_wakeup(ca);
                 break;
         }
 }
@@ -1127,16 +1114,16 @@ static int dvb_ca_en50221_thread(void *data)
                                         break;
                                 }
 
-                                rxbuf = vmalloc(RX_BUFFER_SIZE);
-                                if (rxbuf == NULL) {
-                                        printk("dvb_ca adapter %d: Unable to allocate CAM rx buffer :(\n", ca->dvbdev->adapter->num);
-                                        ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
-                                        dvb_ca_en50221_thread_update_delay(ca);
-                                        break;
+                                if (ca->slot_info[slot].rx_buffer.data == NULL) {
+                                        rxbuf = vmalloc(RX_BUFFER_SIZE);
+                                        if (rxbuf == NULL) {
+                                                printk("dvb_ca adapter %d: Unable to allocate CAM rx buffer :(\n", ca->dvbdev->adapter->num);
+                                                ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
+                                                dvb_ca_en50221_thread_update_delay(ca);
+                                                break;
+                                        }
+                                        dvb_ringbuffer_init(&ca->slot_info[slot].rx_buffer, rxbuf, RX_BUFFER_SIZE);
                                 }
-                                down_write(&ca->slot_info[slot].sem);
-                                dvb_ringbuffer_init(&ca->slot_info[slot].rx_buffer, rxbuf, RX_BUFFER_SIZE);
-                                up_write(&ca->slot_info[slot].sem);
 
                                 ca->pub->slot_ts_enable(ca->pub, slot);
                                 ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_RUNNING;
@@ -1148,11 +1135,7 @@ static int dvb_ca_en50221_thread(void *data)
                                 if (!ca->open)
                                         continue;
 
-                                // no need to poll if the CAM supports IRQs
-                                if (ca->slot_info[slot].da_irq_supported)
-                                        break;
-
-                                // poll mode
+                                // poll slots for data
                                 pktcount = 0;
                                 while ((status = dvb_ca_en50221_read_data(ca, slot, NULL, 0)) > 0) {
                                         if (!ca->open)
@@ -1367,12 +1350,13 @@ exit:
 /**
  * Condition for waking up in dvb_ca_en50221_io_read_condition
  */
-static int dvb_ca_en50221_io_read_condition(struct dvb_ca_private *ca, int *result, int *_slot)
+static int dvb_ca_en50221_io_read_condition(struct dvb_ca_private *ca,
+                                            int *result, int *_slot)
 {
         int slot;
         int slot_count = 0;
         int idx;
-        int fraglen;
+        size_t fraglen;
         int connection_id = -1;
         int found = 0;
         u8 hdr[2];
@@ -1382,10 +1366,7 @@ static int dvb_ca_en50221_io_read_condition(struct dvb_ca_private *ca, int *resu
                 if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_RUNNING)
                         goto nextslot;
 
-                down_read(&ca->slot_info[slot].sem);
-
                 if (ca->slot_info[slot].rx_buffer.data == NULL) {
-                        up_read(&ca->slot_info[slot].sem);
                         return 0;
                 }
 
@@ -1403,10 +1384,7 @@ static int dvb_ca_en50221_io_read_condition(struct dvb_ca_private *ca, int *resu
                         idx = dvb_ringbuffer_pkt_next(&ca->slot_info[slot].rx_buffer, idx, &fraglen);
                 }
 
-                if (!found)
-                        up_read(&ca->slot_info[slot].sem);
-
-              nextslot:
+nextslot:
                 slot = (slot + 1) % ca->slot_count;
                 slot_count++;
         }
@@ -1511,8 +1489,7 @@ static ssize_t dvb_ca_en50221_io_read(struct file *file, char __user * buf,
                 goto exit;
         status = pktlen;
 
-      exit:
-        up_read(&ca->slot_info[slot].sem);
+exit:
         return status;
 }
 
@@ -1544,11 +1521,11 @@ static int dvb_ca_en50221_io_open(struct inode *inode, struct file *file)
         for (i = 0; i < ca->slot_count; i++) {
 
                 if (ca->slot_info[i].slot_state == DVB_CA_SLOTSTATE_RUNNING) {
-                        down_write(&ca->slot_info[i].sem);
                         if (ca->slot_info[i].rx_buffer.data != NULL) {
+                                /* it is safe to call this here without locks because
+                                 * ca->open == 0. Data is not read in this case */
                                 dvb_ringbuffer_flush(&ca->slot_info[i].rx_buffer);
                         }
-                        up_write(&ca->slot_info[i].sem);
                 }
         }
 
@@ -1607,7 +1584,6 @@ static unsigned int dvb_ca_en50221_io_poll(struct file *file, poll_table * wait)
         dprintk("%s\n", __FUNCTION__);
 
         if (dvb_ca_en50221_io_read_condition(ca, &result, &slot) == 1) {
-                up_read(&ca->slot_info[slot].sem);
                 mask |= POLLIN;
         }
 
@@ -1619,7 +1595,6 @@ static unsigned int dvb_ca_en50221_io_poll(struct file *file, poll_table * wait)
         poll_wait(file, &ca->wait_queue, wait);
 
         if (dvb_ca_en50221_io_read_condition(ca, &result, &slot) == 1) {
-                up_read(&ca->slot_info[slot].sem);
                 mask |= POLLIN;
         }
 
@@ -1709,7 +1684,6 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
                 ca->slot_info[i].slot_state = DVB_CA_SLOTSTATE_NONE;
                 atomic_set(&ca->slot_info[i].camchange_count, 0);
                 ca->slot_info[i].camchange_type = DVB_CA_EN50221_CAMCHANGE_REMOVED;
-                init_rwsem(&ca->slot_info[i].sem);
         }
 
         if (signal_pending(current)) {
@@ -1729,7 +1703,7 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
         ca->thread_pid = ret;
         return 0;
 
-      error:
+error:
         if (ca != NULL) {
                 if (ca->dvbdev != NULL)
                         dvb_unregister_device(ca->dvbdev);
@@ -1771,6 +1745,9 @@ void dvb_ca_en50221_release(struct dvb_ca_en50221 *pubca)
 
         for (i = 0; i < ca->slot_count; i++) {
                 dvb_ca_en50221_slot_shutdown(ca, i);
+                if (ca->slot_info[i].rx_buffer.data != NULL) {
+                        vfree(ca->slot_info[i].rx_buffer.data);
+                }
         }
         kfree(ca->slot_info);
         dvb_unregister_device(ca->dvbdev);