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authorAnton Ivanov <aivanov@brocade.com>2015-11-02 16:16:37 +0000
committerRichard Weinberger <richard@nod.at>2015-11-06 22:54:49 +0100
commit2eb5f31bc4ea24bb293e82934cfa1cce9573304b (patch)
tree69c2d1f775babd528d0873660c97d78f52318641 /arch/um/kernel/skas/mmu.c
parente17c6d77b28c6feab446ad6eaec865e8031ed616 (diff)
downloadlinux-2eb5f31bc4ea24bb293e82934cfa1cce9573304b.tar.bz2
um: Switch clocksource to hrtimers
UML is using an obsolete itimer call for all timers and "polls" for kernel space timer firing in its userspace portion resulting in a long list of bugs and incorrect behaviour(s). It also uses ITIMER_VIRTUAL for its timer which results in the timer being dependent on it running and the cpu load. This patch fixes this by moving to posix high resolution timers firing off CLOCK_MONOTONIC and relaying the timer correctly to the UML userspace. Fixes: - crashes when hosts suspends/resumes - broken userspace timers - effecive ~40Hz instead of what they should be. Note - this modifies skas behavior by no longer setting an itimer per clone(). Timer events are relayed instead. - kernel network packet scheduling disciplines - tcp behaviour especially under load - various timer related corner cases Finally, overall responsiveness of userspace is better. Signed-off-by: Thomas Meyer <thomas@m3y3r.de> Signed-off-by: Anton Ivanov <aivanov@brocade.com> [rw: massaged commit message] Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel/skas/mmu.c')
-rw-r--r--arch/um/kernel/skas/mmu.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index fda1deba1757..9591a66aa5c5 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -1,4 +1,5 @@
/*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
@@ -61,10 +62,12 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
if (current->mm != NULL && current->mm != &init_mm)
from_mm = &current->mm->context;
+ block_signals();
if (from_mm)
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
+ unblock_signals();
if (to_mm->id.u.pid < 0) {
ret = to_mm->id.u.pid;