diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/dma/Kconfig | 5 | ||||
| -rw-r--r-- | kernel/dma/debug.c | 55 |
2 files changed, 1 insertions, 59 deletions
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index f4770fcfa62b..5732b2b3ef17 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -186,11 +186,6 @@ config DMA_API_DEBUG drivers like double-freeing of DMA mappings or freeing mappings that were never allocated. - This also attempts to catch cases where a page owned by DMA is - accessed by the cpu in a way that could cause data corruption. For - example, this enables cow_user_page() to check that the source page is - not undergoing DMA. - This option causes a performance degradation. Use only if you want to debug device drivers and dma interactions. diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index f7f807fb6ebb..8e9f7b301c6d 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -448,9 +448,6 @@ void debug_dma_dump_mappings(struct device *dev) * dma_active_cacheline entry to track per event. dma_map_sg(), on the * other hand, consumes a single dma_debug_entry, but inserts 'nents' * entries into the tree. - * - * At any time debug_dma_assert_idle() can be called to trigger a - * warning if any cachelines in the given page are in the active set. */ static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT); static DEFINE_SPINLOCK(radix_lock); @@ -497,10 +494,7 @@ static void active_cacheline_inc_overlap(phys_addr_t cln) overlap = active_cacheline_set_overlap(cln, ++overlap); /* If we overflowed the overlap counter then we're potentially - * leaking dma-mappings. Otherwise, if maps and unmaps are - * balanced then this overflow may cause false negatives in - * debug_dma_assert_idle() as the cacheline may be marked idle - * prematurely. + * leaking dma-mappings. */ WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP, pr_fmt("exceeded %d overlapping mappings of cacheline %pa\n"), @@ -555,53 +549,6 @@ static void active_cacheline_remove(struct dma_debug_entry *entry) spin_unlock_irqrestore(&radix_lock, flags); } -/** - * debug_dma_assert_idle() - assert that a page is not undergoing dma - * @page: page to lookup in the dma_active_cacheline tree - * - * Place a call to this routine in cases where the cpu touching the page - * before the dma completes (page is dma_unmapped) will lead to data - * corruption. - */ -void debug_dma_assert_idle(struct page *page) -{ - static struct dma_debug_entry *ents[CACHELINES_PER_PAGE]; - struct dma_debug_entry *entry = NULL; - void **results = (void **) &ents; - unsigned int nents, i; - unsigned long flags; - phys_addr_t cln; - - if (dma_debug_disabled()) - return; - - if (!page) - return; - - cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT; - spin_lock_irqsave(&radix_lock, flags); - nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln, - CACHELINES_PER_PAGE); - for (i = 0; i < nents; i++) { - phys_addr_t ent_cln = to_cacheline_number(ents[i]); - - if (ent_cln == cln) { - entry = ents[i]; - break; - } else if (ent_cln >= cln + CACHELINES_PER_PAGE) - break; - } - spin_unlock_irqrestore(&radix_lock, flags); - - if (!entry) - return; - - cln = to_cacheline_number(entry); - err_printk(entry->dev, entry, - "cpu touching an active dma mapped cacheline [cln=%pa]\n", - &cln); -} - /* * Wrapper function for adding an entry to the hash. * This function takes care of locking itself. |