[haiku-bugs] Re: [Haiku] #12929: [XHCI] crash in _LinkDescriptorForPipe()

  • From: "Haiku" <trac@xxxxxxxxxxxx>
  • To: undisclosed-recipients: ;
  • Date: Mon, 18 Feb 2019 14:16:03 -0000

#12929: [XHCI] crash in _LinkDescriptorForPipe()
--------------------------------+----------------------------------------
   Reporter:  diver             |      Owner:  nobody
       Type:  bug               |     Status:  assigned
   Priority:  normal            |  Milestone:  R1/beta2
  Component:  Drivers/USB/XHCI  |    Version:  R1/Development
 Resolution:                    |   Keywords:
 Blocked By:                    |   Blocking:  12915, 12951, 13912, 14798
Has a Patch:  0                 |   Platform:  All
--------------------------------+----------------------------------------

Comment (by waddlesplash):

BTW I'm not sure this has to do with this bug, since ATM
 CreateDescriptorChain() returns NULL for a zero buffer length,
 _LinkDescriptorForPipe() shouldn't be called at all. Maybe I misread the
 code.

 Well, if we should make sure trbCount is non-zero, then tdCount will of
 course be 1 in that case, yes?

Control requests actually happen ​here and don't call
 ​CreateDescriptorChain() but ​CreateDescriptor()

 OK, then in that case I really don't understand how we get a page fault
 here.

 Is there a reason we allocate/free descriptors for every request? That
 seems a little slow to say the least.

-- 
Ticket URL: <https://dev.haiku-os.org/ticket/12929#comment:14>
Haiku <https://dev.haiku-os.org>
The Haiku operating system.

Other related posts: