linux-kernel - [patch] x86/iopl: Remove unused local variable, update comments in ksys

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Message-ID: <20191107072826.GB30739@gmail.com>
Date:   Thu, 7 Nov 2019 08:28:26 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Stephen Hemminger <stephen@...workplumber.org>,
        Willy Tarreau <w@....eu>, Juergen Gross <jgross@...e.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [patch] x86/iopl: Remove unused local variable, update comments in
 ksys_ioperm()


* Thomas Gleixner <tglx@...utronix.de> wrote:

> The series is also available from git:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/iopl

Very nice series - I fully agree with this simplification of ioperm 
legacies.


On x86-64 defconfig new warning in ioport.c:

    arch/x86/kernel/ioport.c:184:18: warning: unused variable ‘regs’ [-Wunused-variable]

This local variable can simply be removed, now that we don't rely on 
regs->flags anymore. See the patch below.

I also removed the now stale comment about the Xen PV 
quirk/incompatibility.

Thanks,

	Ingo

---
 arch/x86/kernel/ioport.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index aad296a23170..78127087b1ed 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -181,15 +181,10 @@ SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
 SYSCALL_DEFINE1(iopl, unsigned int, level)
 {
 	struct thread_struct *t = &current->thread;
-	struct pt_regs *regs = current_pt_regs();
 	struct tss_struct *tss;
 	unsigned int tss_base;
 	unsigned int old;
 
-	/*
-	 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
-	 * and changing them has no effect.
-	 */
 	if (IS_ENABLED(CONFIG_X86_IOPL_NONE))
 		return -ENOSYS;