On Thu, Jan 12, 2012 at 10:55:15PM +0100, Jiri Slaby wrote: > Commit 74c2107759d (serial: Use block_til_ready helper) and its fixup > 3f582b8c110 (serial: fix termios settings in open) introduced a > regression on UV systems. The serial eventually freezes while being > used. It's completely unpredictable and sometimes needs a heap of > traffic to happen first. > > To reproduce this, yast installation was used as it turned out to be > pretty reliable in reproducing. Especially during installation process > where one doesn't have an SSH daemon running. And no monitor as the HW > is completely headless. So this was fun to find. Given the machine > doesn't boot on vanilla before 2.6.36 final. (And the commits above > are older.) > > Unless there is some bad race in the code, the hardware seems to be > pretty broken. Otherwise pure MSR read should not cause such a bug, > or? > > So to prevent the bug, revert to the old behavior. I.e. read modem > status only if we really have to -- for non-CLOCAL set serials. > Non-CLOCAL works on this hardware OK, I tried. See? I don't. > > And document that shit. Thanks for tracking this down, I'll queue it up and get it to Linus after 3.3-rc1 is out. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
