From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755219AbeCVPXh (ORCPT ); Thu, 22 Mar 2018 11:23:37 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:39559 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754777AbeCVPW4 (ORCPT ); Thu, 22 Mar 2018 11:22:56 -0400 From: Sebastian Andrzej Siewior To: Joerg Roedel Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, Scott Wood , Sebastian Andrzej Siewior Subject: [PATCH 09/10] iommu/amd: make amd_iommu_devtable_lock a spin_lock Date: Thu, 22 Mar 2018 16:22:41 +0100 Message-Id: <20180322152242.12705-10-bigeasy@linutronix.de> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180322152242.12705-1-bigeasy@linutronix.de> References: <20180322152242.12705-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Before commit 0bb6e243d7fb ("iommu/amd: Support IOMMU_DOMAIN_DMA type allocation") amd_iommu_devtable_lock had a read_lock() user but now there are none. In fact, after the mentioned commit we had only write_lock() user of the lock. Since there is no reason to keep it as writer lock, change its type to a spin_lock. I *think* that we might even be able to remove the lock because all its current user seem to have their own protection. Signed-off-by: Sebastian Andrzej Siewior --- drivers/iommu/amd_iommu.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index c493d345b3ef..23e26a4b708e 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -80,7 +80,7 @@ */ #define AMD_IOMMU_PGSIZES ((~0xFFFUL) & ~(2ULL << 38)) =20 -static DEFINE_RWLOCK(amd_iommu_devtable_lock); +static DEFINE_SPINLOCK(amd_iommu_devtable_lock); static DEFINE_SPINLOCK(pd_bitmap_lock); static DEFINE_SPINLOCK(iommu_table_lock); =20 @@ -2097,9 +2097,9 @@ static int attach_device(struct device *dev, } =20 skip_ats_check: - write_lock_irqsave(&amd_iommu_devtable_lock, flags); + spin_lock_irqsave(&amd_iommu_devtable_lock, flags); ret =3D __attach_device(dev_data, domain); - write_unlock_irqrestore(&amd_iommu_devtable_lock, flags); + spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags); =20 /* * We might boot into a crash-kernel here. The crashed kernel @@ -2149,9 +2149,9 @@ static void detach_device(struct device *dev) domain =3D dev_data->domain; =20 /* lock device table */ - write_lock_irqsave(&amd_iommu_devtable_lock, flags); + spin_lock_irqsave(&amd_iommu_devtable_lock, flags); __detach_device(dev_data); - write_unlock_irqrestore(&amd_iommu_devtable_lock, flags); + spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags); =20 if (!dev_is_pci(dev)) return; @@ -2814,7 +2814,7 @@ static void cleanup_domain(struct protection_domain *= domain) struct iommu_dev_data *entry; unsigned long flags; =20 - write_lock_irqsave(&amd_iommu_devtable_lock, flags); + spin_lock_irqsave(&amd_iommu_devtable_lock, flags); =20 while (!list_empty(&domain->dev_list)) { entry =3D list_first_entry(&domain->dev_list, @@ -2822,7 +2822,7 @@ static void cleanup_domain(struct protection_domain *= domain) __detach_device(entry); } =20 - write_unlock_irqrestore(&amd_iommu_devtable_lock, flags); + spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags); } =20 static void protection_domain_free(struct protection_domain *domain) --=20 2.16.2