On Sat, Mar 02, 2024 at 07:53:12AM +0100, Linux regression tracking (Thorsten Leemhuis) wrote: > [adding the people involved in developing and applying the culprit to > the list of recipients] > > Hi! Thx for the report. > > On 02.03.24 01:27, Chris Yokum wrote: > > We have found a regression bug, where more than 512 URBs cannot be > > reliably submitted to XHCI. URBs beyond that return 0x00 instead of > > valid data in the buffer. You mean 512 outstanding URBS that are not completed? What in-kernel driver does this? > > Our software works reliably on kernel versions through 6.4.x and fails > > on versions 6.5, 6.6, 6.7, and 6.8.0-rc6. This was discovered when > > Ubuntu recently updated their latest kernel package to version 6.5. > > > > The issue is limited to the XHCI driver and appears to be isolated to > > this specific commit: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/usb?h=v6.5&id=f5af638f0609af889f15c700c60b93c06cc76675 <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/usb?h=v6.5&id=f5af638f0609af889f15c700c60b93c06cc76675> > > FWIW, that's f5af638f0609af ("xhci: Fix transfer ring expansion size > calculation") [v6.5-rc1] from Mathias. > > > Attached is a test program that demonstrates the problem. We used a few > > different USB-to-Serial adapters with no driver installed as a > > convenient way to reproduce. We check the TRB debug information before > > and after to verify the actual number of allocated TRBs. Ah, so this is just through usbfs? > > With some adapters on unaffected kernels, the TRB map gets expanded > > correctly. This directly corresponds to correct functional behavior. On > > affected kernels, the TRB ring does not expand, and our functional tests > > also will fail. > > > > We don't know exactly why this happens. Some adapters do work correctly, > > so there seems to also be some subtle problem that was being masked by > > the liberal expansion of the TRB ring in older kernels. We also saw on > > one system that the TRB expansion did work correctly with one particular > > adapter. However, on all systems at least two adapters did exhibit the > > problem and fail. Any chance you can provide the 'lspci' output for the controllers that work and those that do not? thanks, greg k-h
