Messages in this thread | | | Date | Wed, 18 Nov 2015 12:44:26 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] signal: Unexport sigsuspend() |
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On Mon, 16 Nov 2015 19:18:21 +0100 Richard Weinberger <richard@nod.at> wrote:
> sigsuspend() is nowhere used except in signal.c itself, > so we can mark it static do not pollute the global namespace. > > But this patch is more than a boring cleanup patch, > it fixes a real issue on UserModeLinux. > UML has a special console driver to display ttys using xterm, > or other terminal emulators, on the host side. > Vegard reported that sometimes UML is unable to spawn a xterm > and he's facing the following warning: > WARNING: CPU: 0 PID: 908 at include/linux/thread_info.h:128 sigsuspend+0xab/0xc0() > It turned out that this warning makes absolutely no sense as > the UML xterm code calls sigsuspend() on the host side, at least it tries. > But as the kernel itself offers a sigsuspend() symbol the linker choose > this one instead of the glibc wrapper. Interestingly this code used to > work since ever but always blocked signals on the wrong side. > Some recent kernel change made the WARN_ON() trigger and uncovered the bug. >
So we don't know what caused this or when it started happening. hrm. I guess I'll stick a cc:stable in there as it's likely to affect 4.3 and perhaps earlier, OK?
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