Jakob Bornecrantz wrote: > On 1 dec 2009, at 00.24, Robert Noland wrote: > >> On Tue, 2009-12-01 at 10:37 +1100, Daniel Stone wrote: >> >>> On Mon, Nov 30, 2009 at 11:21:47AM -0600, Robert Noland wrote: >>> >>>> I've tried to ask linux folk if this is also true for linux, but the >>>> answer is unclear at this time. >>>> >>> EINTR will be returned to userspace if the syscall needs to be >>> restarted. >>> >> Ok, EINTR is already handled in drmIoctl() as is EAGAIN, so that >> sounds >> like my patch would be correct. >> > > Hmm looks like we need to change bunch of stuff in ttm and the vmwgfx > for that to be true. I still like to get Thomas comments on this > before we do anything drastic. > > Yes, there is some stuff we need to change here, really.
As previously pointed out by people on the dri-devel list (Kristian among others), if the linux kernel returns -ERESTARTSYS, and the kernel cannot restart the system call AND there is a signal pending, the kernel (not libc) will convert it to -EINTR and return to user-space. -ERESTARTSYS may only be returned when there is a signal pending. I'm not sure this is the case with -ERESTART. IIRC I've seen man pages with kernel calls return -ERESTART, but I'm not sure at this point. Best would be to test and see what happens. Having said that. I don't think we should change this *now*. If BSD converts -ERESTART to -EINTR, that will get caught in drmCommandXXX and functionality will be preserved. However, before pushing wmwgfx upstream, and before the Radeon user-space interface is set in stone, we should change the TTM code to return -ERESTARTSYS when a signal is pending, meaning that if it returns to user-space, we'll get an -EINTR. At the same time we could apply the suggested patch. If TTM is ported to BSD, and -ERESTARTSYS doesn't exist in BST, the BSD version should return something that will appear as -EINTR in user space. So to summarize: *) I don't think the patch is correct with the current linux wmw / ttm code. *) We should change the ttm / vmw code ASAP so that the patch becomes correct. When this is done, we should apply it. Thanks, Thomas > Cheers Jakob. > > ------------------------------------------------------------------------------ > Join us December 9, 2009 for the Red Hat Virtual Experience, > a free event focused on virtualization and cloud computing. > Attend in-depth sessions from your desk. Your couch. Anywhere. > http://p.sf.net/sfu/redhat-sfdev2dev > _______________________________________________ > Mesa3d-dev mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/mesa3d-dev > ------------------------------------------------------------------------------ Join us December 9, 2009 for the Red Hat Virtual Experience, a free event focused on virtualization and cloud computing. Attend in-depth sessions from your desk. Your couch. Anywhere. http://p.sf.net/sfu/redhat-sfdev2dev _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
