From 0cb54a3e47cb4baf0bc7463f0a64cfeae5e35697 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 2 Feb 2012 15:38:14 -0500 Subject: USB: debugging code shouldn't alter control flow People have complained that debugging code shouldn't alter the flow of control; it should restrict itself to printing out warnings and error messages. Bowing to popular opinion, this patch (as1518) changes the debugging checks in usb_submit_urb() to follow this guideline. Signed-off-by: Alan Stern Reported-by: Keith Packard CC: Pavel Machek Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/urb.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) (limited to 'drivers/usb/core/urb.c') diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index 909625b91eb3..f4f20c7b7765 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -403,20 +403,17 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags) * cause problems in HCDs if they get it wrong. */ { - unsigned int orig_flags = urb->transfer_flags; unsigned int allowed; static int pipetypes[4] = { PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT }; /* Check that the pipe's type matches the endpoint's type */ - if (usb_pipetype(urb->pipe) != pipetypes[xfertype]) { - dev_err(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n", + if (usb_pipetype(urb->pipe) != pipetypes[xfertype]) + dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n", usb_pipetype(urb->pipe), pipetypes[xfertype]); - return -EPIPE; /* The most suitable error code :-) */ - } - /* enforce simple/standard policy */ + /* Check against a simple/standard policy */ allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK | URB_FREE_BUFFER); switch (xfertype) { @@ -435,14 +432,12 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags) allowed |= URB_ISO_ASAP; break; } - urb->transfer_flags &= allowed; + allowed &= urb->transfer_flags; - /* fail if submitter gave bogus flags */ - if (urb->transfer_flags != orig_flags) { - dev_err(&dev->dev, "BOGUS urb flags, %x --> %x\n", - orig_flags, urb->transfer_flags); - return -EINVAL; - } + /* warn if submitter gave bogus flags */ + if (allowed != urb->transfer_flags) + dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n", + urb->transfer_flags, allowed); } #endif /* -- cgit v1.2.3 From 371f3b49f2cb1a8b6ac09b6b108841ca92349eb1 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 29 Feb 2012 23:04:32 +0100 Subject: usb/core: remove "always" from usb_unlink_urb() kernel doc entry The kernel doc entry for usb_unlink_urb() contains the phrase "This request is always asynchronous.". The "always" leads to the assumption that the ->complete() callback is not called from within usb_unlink_urb(). This is not true. The HCD is allowed to call the ->complete() from within ->urb_dequeue() if it is appropriate for the hardware. This patch updates the kernel doc so usb-device driver authors make sure to drop all locks (and make sure it is okay to drop them) which are acquired by the complete callback before calling usb_unlink_urb(). Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/urb.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/usb/core/urb.c') diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index f4f20c7b7765..7239a73c1b8c 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -527,10 +527,13 @@ EXPORT_SYMBOL_GPL(usb_submit_urb); * a driver's I/O routines to insure that all URB-related activity has * completed before it returns. * - * This request is always asynchronous. Success is indicated by - * returning -EINPROGRESS, at which time the URB will probably not yet - * have been given back to the device driver. When it is eventually - * called, the completion function will see @urb->status == -ECONNRESET. + * This request is asynchronous, however the HCD might call the ->complete() + * callback during unlink. Therefore when drivers call usb_unlink_urb(), they + * must not hold any locks that may be taken by the completion function. + * Success is indicated by returning -EINPROGRESS, at which time the URB will + * probably not yet have been given back to the device driver. When it is + * eventually called, the completion function will see @urb->status == + * -ECONNRESET. * Failure is indicated by usb_unlink_urb() returning any other value. * Unlinking will fail when @urb is not currently "linked" (i.e., it was * never submitted, or it was unlinked before, or the hardware is already -- cgit v1.2.3