diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-07-05 12:50:20 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-07-05 12:50:20 -0700 |
commit | bb5a93aaf25261321db0c499cde7da6ee9d8b164 (patch) | |
tree | c99e1b0fea8e3d3fe0b6013a550203ac8b740997 /arch/x86/kernel/ldt.c | |
parent | 72674d480076067d627e708c0a062dd900438bd7 (diff) | |
download | linux-stable-bb5a93aaf25261321db0c499cde7da6ee9d8b164.tar.gz linux-stable-bb5a93aaf25261321db0c499cde7da6ee9d8b164.tar.bz2 linux-stable-bb5a93aaf25261321db0c499cde7da6ee9d8b164.zip |
x86/ldt: use "pr_info_once()" instead of open-coding it badly
Using a mutex for "print this warning only once" is so overdesigned as
to be actively offensive to my sensitive stomach.
Just use "pr_info_once()" that already does this, although in a
(harmlessly) racy manner that can in theory cause the message to be
printed twice if more than one CPU races on that "is this the first
time" test.
[ If somebody really cares about that harmless data race (which sounds
very unlikely indeed), that person can trivially fix printk_once() by
using a simple atomic access, preferably with an optimistic non-atomic
test first before even bothering to treat the pointless "make sure it
is _really_ just once" case.
A mutex is most definitely never the right primitive to use for
something like this. ]
Yes, this is a small and meaningless detail in a code path that hardly
matters. But let's keep some code quality standards here, and not
accept outrageously bad code.
Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/kernel/ldt.c')
-rw-r--r-- | arch/x86/kernel/ldt.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index 34e918ad34d4..b8aee71840ae 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -559,16 +559,7 @@ static bool allow_16bit_segments(void) * is worthwhile, disallow 16-bit segments under Xen PV. */ if (xen_pv_domain()) { - static DEFINE_MUTEX(xen_warning); - static bool warned; - - mutex_lock(&xen_warning); - if (!warned) { - pr_info("Warning: 16-bit segments do not work correctly in a Xen PV guest\n"); - warned = true; - } - mutex_unlock(&xen_warning); - + pr_info_once("Warning: 16-bit segments do not work correctly in a Xen PV guest\n"); return false; } #endif |