[linux-dvb] vfree during spin_lock hold (Was: (In)consistency of DMX/DVR buffers and OSD ioctls)

[Dr. Werner Fink]

Hi,

     during seeking for a better protection against dropouts of
of a PES filter for DMX_PES_OTHER (AC3) using DMX_OUT_TAP caused
by OSD popups, I've seen that within DmxDevSetBufferSize() in
dmxdev.c that vfree() is called within a spin_lock_irq/spin_unlock_irq
pair.  This seems to be a bug.  Enclosed a patch which changes this.
Also changed in this patch: hold spin_lock in DmxDevTSCallback()
during copy buffers (seems to decrease dropouts caused by other
activities on the system), use reparent_to_init() for the
kernel threads "arm_mon" and "fe_thread".

             Werner

-----------------------------------------------------------------------
--- dmxdev.c
+++ dmxdev.c    Wed Mar 27 11:54:02 2002
@@ -288,18 +288,19 @@
 DmxDevSetBufferSize(dmxdev_filter_t *dmxdevfilter, unsigned long size)
 {
        dmxdev_buffer_t *buf=&dmxdevfilter->buffer;
+       void *mem=buffer->data;
 
        if (buf->size==size)
                return 0;
         if (dmxdevfilter->state>=DMXDEV_STATE_GO)
                 return -EBUSY;
        spin_lock_irq(&dmxdevfilter->dev->lock);
-        if (buf->data) 
-               vfree(buf->data);
        buf->data=0;
        buf->size=size;
        buf->pwrite=buf->pread=0;    
        spin_unlock_irq(&dmxdevfilter->dev->lock);
+       if (mem) 
+               vfree(mem);
                
         if (buf->size) {
                void *mem=vmalloc(dmxdevfilter->buffer.size);
@@ -384,18 +385,21 @@
         dmxdev_filter_t *dmxdevfilter=(dmxdev_filter_t *) feed->priv;
        dmxdev_buffer_t *buffer;
         int ret;
-        
-       if (dmxdevfilter->params.pes.output==DMX_OUT_DECODER)
-               return 0;
+
+       spin_lock(&dmxdevfilter->dev->lock);
+       if (dmxdevfilter->params.pes.output==DMX_OUT_DECODER) {
+               spin_unlock(&dmxdevfilter->dev->lock);
+               return 0;
+       }
 
        if (dmxdevfilter->params.pes.output==DMX_OUT_TAP)
                buffer=&dmxdevfilter->buffer;
        else
                buffer=&dmxdevfilter->dev->dvr_buffer;
-       if (buffer->error) {
-               wake_up(&buffer->queue);
-               return 0;
-       }
+
+       if (buffer->error)
+               goto out;
+
         ret=DmxDevBufferWrite(buffer, buffer1, buffer1_len);
         if (ret==buffer1_len) 
                ret=DmxDevBufferWrite(buffer, buffer2, buffer2_len);
@@ -403,6 +407,8 @@
                buffer->pwrite=buffer->pread;    
                buffer->error=-EBUFFEROVERFLOW;
        }
+out:
+       spin_unlock(&dmxdevfilter->dev->lock);
        wake_up(&buffer->queue);
        return 0;
 }
--- dvb.c
+++ dvb.c       Wed Mar 27 11:49:06 2002
@@ -427,13 +427,19 @@
         u16 newloops;
     
        lock_kernel();
-#if 0
+#if 1
        daemonize();
+       reparent_to_init();
+
 #else
         exit_mm(current);
         current->session=current->pgrp=1;
 #endif
+       spin_lock_irq(&current->sigmask_lock);
        sigfillset(&current->blocked);
+       recalc_sigpending(current);
+       spin_unlock_irq(&current->sigmask_lock);
+
        strcpy(current->comm, "arm_mon");
        dvb->arm_thread = current;
        unlock_kernel();
--- dvb_frontend.c
+++ dvb_frontend.c      Wed Mar 27 11:49:06 2002
@@ -431,7 +431,13 @@
     
        lock_kernel();
        daemonize();
+       reparent_to_init();
+
+       spin_lock_irq(&current->sigmask_lock);
        sigfillset(&current->blocked);
+       recalc_sigpending(current);
+       spin_unlock_irq(&current->sigmask_lock);
+
        strcpy(current->comm,"fe_thread");
        fe->thread = current;
        unlock_kernel();


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