From: Borislav Petkov <bp@alien8.de>
To: Oleg Nesterov <oleg@redhat.com>, Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave@sr71.net>,
linux-kernel@vger.kernel.org, x86@kernel.org,
dave.hansen@linux.intel.com, riel@redhat.com, sbsiddha@gmail.com,
luto@amacapital.net, mingo@redhat.com, hpa@zytor.com,
fenghua.yu@intel.com
Subject: Re: [PATCH 01/16] x86, fpu: wrap get_xsave_addr() to make it safer
Date: Wed, 22 Apr 2015 17:58:40 +0200 [thread overview]
Message-ID: <20150422155840.GJ6897@pd.tnic> (raw)
In-Reply-To: <20150422153245.GA22825@redhat.com>
On Wed, Apr 22, 2015 at 05:32:45PM +0200, Oleg Nesterov wrote:
> How? I am certainly missing you point... OK, please forge about FPU.
> Consider this code:
>
> tsk = current;
> for (;;)
> BUG_ON(tsk != current);
>
> it doesn't need to disable preemption. We do not care if CPU switches
> to another thread, even if this thread executes the same code. Because
> its tsk/current will differ, but "tsk == current" will be still true.
>
> Could you please spell?
Bah, forget what I said. tglx schooled me on IRC. We always do get
called with tsk == current. Sorry for the confusion...
> See above... used_math() should be correct because we know that tsk==current,
> but I agree that tsk_used_math(tsk) looks better.
Right, and it is clear what's going on, even to lusers like me.
Thanks for teaching me guys.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-04-22 15:58 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-01 0:46 [PATCH 00/16] x86, mpx updates for 4.1 (take 4) Dave Hansen
2015-04-01 0:46 ` [PATCH 01/16] x86, fpu: wrap get_xsave_addr() to make it safer Dave Hansen
2015-04-22 10:40 ` Borislav Petkov
2015-04-22 13:16 ` Oleg Nesterov
2015-04-22 13:31 ` Borislav Petkov
2015-04-22 14:56 ` Dave Hansen
2015-04-22 15:17 ` Thomas Gleixner
2015-04-22 15:21 ` Borislav Petkov
2015-04-22 15:26 ` Thomas Gleixner
2015-04-22 16:02 ` Dave Hansen
2015-04-22 15:32 ` Oleg Nesterov
2015-04-22 15:58 ` Borislav Petkov [this message]
2015-04-01 0:46 ` [PATCH 02/16] x86, mpx: use new tsk_get_xsave_addr() Dave Hansen
2015-04-01 0:46 ` [PATCH 03/16] x86, mpx: trace #BR exceptions Dave Hansen
2015-04-01 0:46 ` [PATCH 04/16] x86, mpx: trace entry to bounds exception paths Dave Hansen
2015-04-01 0:46 ` [PATCH 05/16] x86, mpx: trace ranged MPX operations Dave Hansen
2015-04-01 0:46 ` [PATCH 06/16] x86, mpx: trace allocation of new bounds tables Dave Hansen
2015-04-01 0:46 ` [PATCH 07/16] x86, mpx: boot-time disable Dave Hansen
2015-04-01 0:46 ` [PATCH 08/16] x86: make is_64bit_mm() widely available Dave Hansen
2015-04-01 0:46 ` [PATCH 09/16] x86: make __VIRTUAL_MASK safe to use on 32 bit Dave Hansen
2015-04-01 0:46 ` [PATCH 10/16] x86, mpx: we do not allocate the bounds directory Dave Hansen
2015-04-01 0:46 ` [PATCH 11/16] x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK Dave Hansen
2015-04-01 0:46 ` [PATCH 12/16] x86, mpx: Add temporary variable to reduce masking Dave Hansen
2015-04-01 0:46 ` [PATCH 13/16] x86, mpx: new directory entry to addr helper Dave Hansen
2015-04-01 0:46 ` [PATCH 14/16] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-04-01 0:46 ` [PATCH 15/16] x86, mpx: support 32-bit binaries on 64-bit kernel Dave Hansen
2015-04-01 0:46 ` [PATCH 16/16] x86, mpx: allow mixed binaries again Dave Hansen
2015-04-21 15:39 ` [PATCH 00/16] x86, mpx updates for 4.1 (take 4) Dave Hansen
2015-04-22 10:49 ` Borislav Petkov
2015-04-22 14:43 ` Dave Hansen
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