linux-kernel - [tip:x86/apic] x86/idt: Simplify alloc_intr

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Message-ID: <tip-4447ac1195a845b18f2f427686f116ab77c5b268@git.kernel.org>
Date:   Tue, 29 Aug 2017 04:21:15 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jgross@...e.com, sthemmin@...rosoft.com, luto@...nel.org,
        rostedt@...dmis.org, boris.ostrovsky@...cle.com,
        jpoimboe@...hat.com, peterz@...radead.org,
        torvalds@...ux-foundation.org, kys@...rosoft.com,
        brgerst@...il.com, bp@...en8.de, tglx@...utronix.de, hpa@...or.com,
        linux-kernel@...r.kernel.org, dvlasenk@...hat.com, mingo@...nel.org
Subject: [tip:x86/apic] x86/idt: Simplify alloc_intr_gate()

Commit-ID:  4447ac1195a845b18f2f427686f116ab77c5b268
Gitweb:     http://git.kernel.org/tip/4447ac1195a845b18f2f427686f116ab77c5b268
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Mon, 28 Aug 2017 08:47:58 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 29 Aug 2017 12:07:28 +0200

x86/idt: Simplify alloc_intr_gate()

The only users of alloc_intr_gate() are hypervisors, which both check the
used_vectors bitmap whether they have allocated the gate already. Move that
check into alloc_intr_gate() and simplify the users.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Juergen Gross <jgross@...e.com>
Reviewed-by: K. Y. Srinivasan <kys@...rosoft.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/r/20170828064959.580830286@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/mshyperv.c   | 9 ++-------
 arch/x86/kernel/idt.c            | 6 +++---
 drivers/xen/events/events_base.c | 6 ++----
 3 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 70e717f..9fc3265 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -59,13 +59,8 @@ void hyperv_vector_handler(struct pt_regs *regs)
 void hv_setup_vmbus_irq(void (*handler)(void))
 {
 	vmbus_handler = handler;
-	/*
-	 * Setup the IDT for hypervisor callback. Prevent reallocation
-	 * at module reload.
-	 */
-	if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
-		alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
-				hyperv_callback_vector);
+	/* Setup the IDT for hypervisor callback */
+	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
 }
 
 void hv_remove_vmbus_irq(void)
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 8e9318d..b609eac 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -354,7 +354,7 @@ void set_intr_gate(unsigned int n, const void *addr)
 
 void alloc_intr_gate(unsigned int n, const void *addr)
 {
-	BUG_ON(test_bit(n, used_vectors) || n < FIRST_SYSTEM_VECTOR);
-	set_bit(n, used_vectors);
-	set_intr_gate(n, addr);
+	BUG_ON(n < FIRST_SYSTEM_VECTOR);
+	if (!test_and_set_bit(n, used_vectors))
+		set_intr_gate(n, addr);
 }
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 2d43118..1ab4bd1 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1653,10 +1653,8 @@ void xen_callback_vector(void)
 			return;
 		}
 		pr_info("Xen HVM callback vector for event delivery is enabled\n");
-		/* in the restore case the vector has already been allocated */
-		if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
-			alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
-					xen_hvm_callback_vector);
+		alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
+				xen_hvm_callback_vector);
 	}
 }
 #else