Am 18.11.2015 um 21:47 schrieb Richard Weinberger: > Am 18.11.2015 um 21:44 schrieb Andrew Morton: >> On Mon, 16 Nov 2015 19:18:21 +0100 Richard Weinberger <[email protected]> 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? > > I fear it has been this way for ever.
Did some research. It is not that bad. It broke in v3.5 because of this commit: commit 68f3f16d9ad0f1e28ab3fd0001ab5798c41f15a3 Author: Al Viro <[email protected]> Date: Mon May 21 21:42:32 2012 -0400 new helper: sigsuspend() guts of saved_sigmask-based sigsuspend/rt_sigsuspend. Takes kernel sigset_t *. Open-coded instances replaced with calling it Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
