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SubjectRe: [linux-usb-devel] Patch for usb-storage in 2.4
Off the cuff, this doesn't look bad... tho it does a lot.

The reordering of locking in device_reset and bus reset definately looks
good, especially for the corner-cases (yanked device, etc.).

I'm uncertain if your handling of the io_request_lock is right.... but
getting information on how to handle that has been like pulling teeth, so
I'm inclined to trust your wide-scale testing on this.
Was there a reason to add more do-nothing code to host_reset?

Is it really safe to remove the irq_urb_sem?

Also, please make sure everything is CC'ed to the usb-storage list (on this
message).

Matt

On Fri, Apr 09, 2004 at 07:59:43PM -0700, Pete Zaitcev wrote:
> Guys,
>
> this works dandy for us in RHL and RHEL, *especially* on bigger SMP boxes.
> It does not fix all the bugs in that code, but I consider it a good start,
> and unless someone speaks up, it goes to Marcelo after 2.4.26 is out.
> Or maybe before, depending how long it takes him to release 2.4.26.
> Please review, test, etc.
>
> I am working on two new bugs in usb-storage right now, but I'd like
> to have things going in gradually, in self-contained chunks, Viro style.
> Those two are not fixed yet anyway.
>
> -- Pete
>
> diff -urN -X dontdiff linux-2.4.26-rc2/drivers/usb/storage/scsiglue.c linux-2.4.26-rc2-nip/drivers/usb/storage/scsiglue.c
> --- linux-2.4.26-rc2/drivers/usb/storage/scsiglue.c 2004-04-09 17:28:30.000000000 -0700
> +++ linux-2.4.26-rc2-nip/drivers/usb/storage/scsiglue.c 2004-04-09 17:31:44.000000000 -0700
> @@ -218,7 +218,14 @@
> US_DEBUGP("device_reset() called\n" );
>
> spin_unlock_irq(&io_request_lock);
> + down(&(us->dev_semaphore));
> + if (!us->pusb_dev) {
> + up(&(us->dev_semaphore));
> + spin_lock_irq(&io_request_lock);
> + return SUCCESS;
> + }
> rc = us->transport_reset(us);
> + up(&(us->dev_semaphore));
> spin_lock_irq(&io_request_lock);
> return rc;
> }
> @@ -235,27 +242,32 @@
> /* we use the usb_reset_device() function to handle this for us */
> US_DEBUGP("bus_reset() called\n");
>
> + spin_unlock_irq(&io_request_lock);
> +
> + down(&(us->dev_semaphore));
> +
> /* if the device has been removed, this worked */
> if (!us->pusb_dev) {
> US_DEBUGP("-- device removed already\n");
> + up(&(us->dev_semaphore));
> + spin_lock_irq(&io_request_lock);
> return SUCCESS;
> }
>
> - spin_unlock_irq(&io_request_lock);
> -
> /* release the IRQ, if we have one */
> - down(&(us->irq_urb_sem));
> if (us->irq_urb) {
> US_DEBUGP("-- releasing irq URB\n");
> result = usb_unlink_urb(us->irq_urb);
> US_DEBUGP("-- usb_unlink_urb() returned %d\n", result);
> }
> - up(&(us->irq_urb_sem));
>
> /* attempt to reset the port */
> if (usb_reset_device(us->pusb_dev) < 0) {
> - spin_lock_irq(&io_request_lock);
> - return FAILED;
> + /*
> + * Do not return errors, or else the error handler might
> + * invoke host_reset, which is not implemented.
> + */
> + goto bail_out;
> }
>
> /* FIXME: This needs to lock out driver probing while it's working
> @@ -286,28 +298,36 @@
> up(&intf->driver->serialize);
> }
>
> +bail_out:
> /* re-allocate the IRQ URB and submit it to restore connectivity
> * for CBI devices
> */
> if (us->protocol == US_PR_CBI) {
> - down(&(us->irq_urb_sem));
> us->irq_urb->dev = us->pusb_dev;
> result = usb_submit_urb(us->irq_urb);
> US_DEBUGP("usb_submit_urb() returns %d\n", result);
> - up(&(us->irq_urb_sem));
> }
> -
> +
> + up(&(us->dev_semaphore));
> +
> spin_lock_irq(&io_request_lock);
>
> US_DEBUGP("bus_reset() complete\n");
> return SUCCESS;
> }
>
> -/* FIXME: This doesn't do anything right now */
> static int host_reset( Scsi_Cmnd *srb )
> {
> - printk(KERN_CRIT "usb-storage: host_reset() requested but not implemented\n" );
> - return FAILED;
> + struct us_data *us = (struct us_data *)srb->host->hostdata[0];
> +
> + spin_unlock_irq(&io_request_lock);
> + down(&(us->dev_semaphore));
> + printk(KERN_CRIT "usb-storage: host_reset() requested but hardly implemented\n" );
> + up(&(us->dev_semaphore));
> + spin_lock_irq(&io_request_lock);
> + US_DEBUGP("host_reset() complete\n");
> +
> + return SUCCESS;
> }
>
> /***********************************************************************
> diff -urN -X dontdiff linux-2.4.26-rc2/drivers/usb/storage/usb.c linux-2.4.26-rc2-nip/drivers/usb/storage/usb.c
> --- linux-2.4.26-rc2/drivers/usb/storage/usb.c 2004-02-26 14:09:59.000000000 -0800
> +++ linux-2.4.26-rc2-nip/drivers/usb/storage/usb.c 2004-04-09 17:31:45.000000000 -0700
> @@ -501,6 +501,9 @@
> * strucuture is current. This includes the ep_int field, which gives us
> * the endpoint for the interrupt.
> * Returns non-zero on failure, zero on success
> + *
> + * ss->dev_semaphore is expected taken, except for a newly minted,
> + * unregistered device.
> */
> static int usb_stor_allocate_irq(struct us_data *ss)
> {
> @@ -510,13 +513,9 @@
>
> US_DEBUGP("Allocating IRQ for CBI transport\n");
>
> - /* lock access to the data structure */
> - down(&(ss->irq_urb_sem));
> -
> /* allocate the URB */
> ss->irq_urb = usb_alloc_urb(0);
> if (!ss->irq_urb) {
> - up(&(ss->irq_urb_sem));
> US_DEBUGP("couldn't allocate interrupt URB");
> return 1;
> }
> @@ -537,12 +536,9 @@
> US_DEBUGP("usb_submit_urb() returns %d\n", result);
> if (result) {
> usb_free_urb(ss->irq_urb);
> - up(&(ss->irq_urb_sem));
> return 2;
> }
>
> - /* unlock the data structure and return success */
> - up(&(ss->irq_urb_sem));
> return 0;
> }
>
> @@ -772,7 +768,6 @@
> init_completion(&(ss->notify));
> init_MUTEX_LOCKED(&(ss->ip_waitq));
> spin_lock_init(&(ss->queue_exclusion));
> - init_MUTEX(&(ss->irq_urb_sem));
> init_MUTEX(&(ss->current_urb_sem));
> init_MUTEX(&(ss->dev_semaphore));
>
> @@ -1063,7 +1058,6 @@
> down(&(ss->dev_semaphore));
>
> /* release the IRQ, if we have one */
> - down(&(ss->irq_urb_sem));
> if (ss->irq_urb) {
> US_DEBUGP("-- releasing irq URB\n");
> result = usb_unlink_urb(ss->irq_urb);
> @@ -1071,7 +1065,6 @@
> usb_free_urb(ss->irq_urb);
> ss->irq_urb = NULL;
> }
> - up(&(ss->irq_urb_sem));
>
> /* free up the main URB for this device */
> US_DEBUGP("-- releasing main URB\n");
> diff -urN -X dontdiff linux-2.4.26-rc2/drivers/usb/storage/usb.h linux-2.4.26-rc2-nip/drivers/usb/storage/usb.h
> --- linux-2.4.26-rc2/drivers/usb/storage/usb.h 2003-11-29 19:23:15.000000000 -0800
> +++ linux-2.4.26-rc2-nip/drivers/usb/storage/usb.h 2004-04-09 17:51:44.000000000 -0700
> @@ -116,7 +116,7 @@
> struct us_data *next; /* next device */
>
> /* the device we're working with */
> - struct semaphore dev_semaphore; /* protect pusb_dev */
> + struct semaphore dev_semaphore; /* protect many things */
> struct usb_device *pusb_dev; /* this usb_device */
>
> unsigned int flags; /* from filter initially */
> @@ -162,7 +162,6 @@
> atomic_t ip_wanted[1]; /* is an IRQ expected? */
>
> /* interrupt communications data */
> - struct semaphore irq_urb_sem; /* to protect irq_urb */
> struct urb *irq_urb; /* for USB int requests */
> unsigned char irqbuf[2]; /* buffer for USB IRQ */
> unsigned char irqdata[2]; /* data from USB IRQ */
>
>
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--
Matthew Dharm Home: mdharm-usb@one-eyed-alien.net
Maintainer, Linux USB Mass Storage Driver

Department of Justice agent. I have come to purify the flock.
-- DOJ agent
User Friendly, 5/22/1998
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