From: Anna-Maria Gleixner Subject: [PATCH] iommu/amd: Remove redundant WARN_ON() Date: Fri, 20 Jul 2018 10:45:45 +0200 Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz The WARN_ON() was introduced in commit 272e4f99e966 ("iommu/amd: WARN when __[attach|detach]_device are called with irqs enabled") to ensure that the domain->lock is taken in proper irqs disabled context. This is required, because the domain->lock is taken as well in irq context. The proper context check by the WARN_ON() is redundant, because it is already covered by LOCKDEP. When working with locks and changing context, a run with LOCKDEP is required anyway and would detect the wrong lock context. Furthermore all callers for those functions are within the same file and all callers acquire another lock which already disables interrupts. Signed-off-by: Anna-Maria Gleixner Signed-off-by: Sebastian Andrzej Siewior --- drivers/iommu/amd_iommu.c | 12 ------------ 1 file changed, 12 deletions(-) --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -1944,12 +1944,6 @@ static int __attach_device(struct iommu_ { int ret; - /* - * Must be called with IRQs disabled. Warn here to detect early - * when its not. - */ - WARN_ON(!irqs_disabled()); - /* lock domain */ spin_lock(&domain->lock); @@ -2115,12 +2109,6 @@ static void __detach_device(struct iommu { struct protection_domain *domain; - /* - * Must be called with IRQs disabled. Warn here to detect early - * when its not. - */ - WARN_ON(!irqs_disabled()); - domain = dev_data->domain; spin_lock(&domain->lock);