Messages in this thread Patch in this message | | | Date | Mon, 12 Sep 2011 16:37:16 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [GIT PULL] Little bugfix to prevent recursion with tracing timestamps |
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[ Sigh, for some reason that doesn't verify. Let's see if this works. Anyway, I pushed a signed tag "upstream-bugfix-for-linus" on that changeset. - J ]
Hi Linus,
When starting a PV kernel under Xen with full boot-time trace testing enabled, it crashes due to infinite recursion. In principle it could happen at other times too (when just using preempt tracing perhaps?). This fixes it.
BTW, I think this same problem also affects KVM.
Erm, I'm not sure how to authenticate this github as being really from me; I'm signing the mail with my long-standing pgp key in the hope that it helps... Also, the patch is self-evident.
Thanks, J
The following changes since commit b6fd41e29dea9c6753b1843a77e50433e6123bcb:
Linux 3.1-rc6 (2011-09-12 14:02:02 -0700)
are available in the git repository at: git://github.com/jsgf/linux-xen.git upstream/bugfix
Jeremy Fitzhardinge (1): xen: use non-tracing preempt in xen_clocksource_read()
arch/x86/xen/time.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 5158c50..163b467 100644 - - --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -168,9 +168,10 @@ cycle_t xen_clocksource_read(void) struct pvclock_vcpu_time_info *src; cycle_t ret; - - - src = &get_cpu_var(xen_vcpu)->time; + preempt_disable_notrace(); + src = &__get_cpu_var(xen_vcpu)->time; ret = pvclock_clocksource_read(src); - - - put_cpu_var(xen_vcpu); + preempt_enable_notrace(); return ret; } -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEkBAEBCAAGBQJObpesAAoJEAUkni6MUg7HMnAIP0bR68/akTif/RVfis0Cot/a ONlz5GsGGA7AlHfp/l/M8GZo5fUIC7Ja+EqTnpUWMNbubLoe5kALt5k/uQwADtoI cyvi5j2tlXDGDZOgQ900pQQYMBFVwaCm5XwSuDTbysPUx4v7E5Ha/RL2xapbuFnP txCyO62xx4EsKqkupM4qnTCBId6ksRNo9EVESxFzpJk/l0fabTLM98RigA1KJmdo +Rr+1SzfNnNQLLXG48EHITthfYaBOw9jyGanbe5i9Iw79J85vjI5V65TMlDztWaN kyUGiWD9f1i9ixCO31qhszdRire8c2N8hDTTN5z1919Gtlkq93Oj3F8zkUlbapyh tD4e8GObdA== =MA3l -----END PGP SIGNATURE-----
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