diff options
| author | Robin Murphy <robin.murphy@arm.com> | 2019-12-09 22:47:25 +0300 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2019-12-18 19:41:36 +0300 |
| commit | c18647900ec864d401ba09b3bbd5b34f331f8d26 (patch) | |
| tree | 19396b8c23761f2938e787b8b7c970705d978b7b /drivers/iommu/dma-iommu.c | |
| parent | f81b846dcd9a1e6d120f73970a9a98b7fcaaffba (diff) | |
| download | linux-c18647900ec864d401ba09b3bbd5b34f331f8d26.tar.xz | |
iommu/dma: Relax locking in iommu_dma_prepare_msi()
Since commit ece6e6f0218b ("iommu/dma-iommu: Split iommu_dma_map_msi_msg()
in two parts"), iommu_dma_prepare_msi() should no longer have to worry
about preempting itself, nor being called in atomic context at all. Thus
we can downgrade the IRQ-safe locking to a simple mutex to avoid angering
the new might_sleep() check in iommu_map().
Reported-by: Qian Cai <cai@lca.pw>
Tested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/dma-iommu.c')
| -rw-r--r-- | drivers/iommu/dma-iommu.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 6e573d1cb8bf..c363294b3bb9 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -19,6 +19,7 @@ #include <linux/iova.h> #include <linux/irq.h> #include <linux/mm.h> +#include <linux/mutex.h> #include <linux/pci.h> #include <linux/scatterlist.h> #include <linux/vmalloc.h> @@ -44,7 +45,6 @@ struct iommu_dma_cookie { dma_addr_t msi_iova; }; struct list_head msi_page_list; - spinlock_t msi_lock; /* Domain for flush queue callback; NULL if flush queue not in use */ struct iommu_domain *fq_domain; @@ -63,7 +63,6 @@ static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type) cookie = kzalloc(sizeof(*cookie), GFP_KERNEL); if (cookie) { - spin_lock_init(&cookie->msi_lock); INIT_LIST_HEAD(&cookie->msi_page_list); cookie->type = type; } @@ -1176,7 +1175,7 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev, if (msi_page->phys == msi_addr) return msi_page; - msi_page = kzalloc(sizeof(*msi_page), GFP_ATOMIC); + msi_page = kzalloc(sizeof(*msi_page), GFP_KERNEL); if (!msi_page) return NULL; @@ -1206,7 +1205,7 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) struct iommu_domain *domain = iommu_get_domain_for_dev(dev); struct iommu_dma_cookie *cookie; struct iommu_dma_msi_page *msi_page; - unsigned long flags; + static DEFINE_MUTEX(msi_prepare_lock); /* see below */ if (!domain || !domain->iova_cookie) { desc->iommu_cookie = NULL; @@ -1216,13 +1215,13 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) cookie = domain->iova_cookie; /* - * We disable IRQs to rule out a possible inversion against - * irq_desc_lock if, say, someone tries to retarget the affinity - * of an MSI from within an IPI handler. + * In fact the whole prepare operation should already be serialised by + * irq_domain_mutex further up the callchain, but that's pretty subtle + * on its own, so consider this locking as failsafe documentation... */ - spin_lock_irqsave(&cookie->msi_lock, flags); + mutex_lock(&msi_prepare_lock); msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain); - spin_unlock_irqrestore(&cookie->msi_lock, flags); + mutex_unlock(&msi_prepare_lock); msi_desc_set_iommu_cookie(desc, msi_page); |