From 01ce18b31153427bcdccc9c9fd170fd28c03e6e8 Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Wed, 10 Dec 2014 15:41:23 -0800 Subject: dma-debug: introduce dma_debug_disabled Add a helper function which returns whether the DMA debugging API is disabled, right now we only check for global_disable, but in order to accommodate early callers of the DMA-API, we will check for more initialization flags in the next patch. Signed-off-by: Florian Fainelli Cc: Dan Williams Cc: Jiri Kosina Cc: Horia Geanta Cc: Brian Norris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/dma-debug.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) (limited to 'lib/dma-debug.c') diff --git a/lib/dma-debug.c b/lib/dma-debug.c index add80cc02dbe..1ac35dbaf8e0 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -102,6 +102,11 @@ static DEFINE_SPINLOCK(free_entries_lock); /* Global disable flag - will be set in case of an error */ static u32 global_disable __read_mostly; +static inline bool dma_debug_disabled(void) +{ + return global_disable; +} + /* Global error count */ static u32 error_count; @@ -945,7 +950,7 @@ static int dma_debug_device_change(struct notifier_block *nb, unsigned long acti struct dma_debug_entry *uninitialized_var(entry); int count; - if (global_disable) + if (dma_debug_disabled()) return 0; switch (action) { @@ -973,7 +978,7 @@ void dma_debug_add_bus(struct bus_type *bus) { struct notifier_block *nb; - if (global_disable) + if (dma_debug_disabled()) return; nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL); @@ -994,7 +999,7 @@ void dma_debug_init(u32 num_entries) { int i; - if (global_disable) + if (dma_debug_disabled()) return; for (i = 0; i < HASH_SIZE; ++i) { @@ -1243,7 +1248,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset, { struct dma_debug_entry *entry; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; if (dma_mapping_error(dev, dma_addr)) @@ -1283,7 +1288,7 @@ void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr) struct hash_bucket *bucket; unsigned long flags; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; ref.dev = dev; @@ -1325,7 +1330,7 @@ void debug_dma_unmap_page(struct device *dev, dma_addr_t addr, .direction = direction, }; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; if (map_single) @@ -1342,7 +1347,7 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg, struct scatterlist *s; int i; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; for_each_sg(sg, s, mapped_ents, i) { @@ -1395,7 +1400,7 @@ void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist, struct scatterlist *s; int mapped_ents = 0, i; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; for_each_sg(sglist, s, nelems, i) { @@ -1427,7 +1432,7 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size, { struct dma_debug_entry *entry; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; if (unlikely(virt == NULL)) @@ -1462,7 +1467,7 @@ void debug_dma_free_coherent(struct device *dev, size_t size, .direction = DMA_BIDIRECTIONAL, }; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; check_unmap(&ref); @@ -1474,7 +1479,7 @@ void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, { struct dma_debug_entry ref; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; ref.type = dma_debug_single; @@ -1494,7 +1499,7 @@ void debug_dma_sync_single_for_device(struct device *dev, { struct dma_debug_entry ref; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; ref.type = dma_debug_single; @@ -1515,7 +1520,7 @@ void debug_dma_sync_single_range_for_cpu(struct device *dev, { struct dma_debug_entry ref; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; ref.type = dma_debug_single; @@ -1536,7 +1541,7 @@ void debug_dma_sync_single_range_for_device(struct device *dev, { struct dma_debug_entry ref; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; ref.type = dma_debug_single; @@ -1556,7 +1561,7 @@ void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, struct scatterlist *s; int mapped_ents = 0, i; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; for_each_sg(sg, s, nelems, i) { @@ -1589,7 +1594,7 @@ void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, struct scatterlist *s; int mapped_ents = 0, i; - if (unlikely(global_disable)) + if (unlikely(dma_debug_disabled())) return; for_each_sg(sg, s, nelems, i) { -- cgit v1.2.2 From 2ce8e7ed006a6e86eecf59188da8652b8a3bc4f0 Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Wed, 10 Dec 2014 15:41:25 -0800 Subject: dma-debug: prevent early callers from crashing dma_debug_init() is called by architecture specific code at different levels, but typically as a fs_initcall due to the debugfs initialization. Some platforms may have early callers of the DMA-API, running prior to the fs_initcall() level, which is not much of an issue unless CONFIG_DMA_API_DEBUG is set. When the DMA-API debugging facilities are turned on a caller will go through: debug_dma_map_{single,page} -> dma_mapping_error (inline function usually) -> debug_dma_mapping_error -> get_hash_bucket Calling get_hash_bucket() returns a valid hash value since we hash on high bits of the dma_addr cookie, but we will grab an unitialized spinlock, which typically won't crash but produce a warning, the real crash will however happen during the bucket list traversal because the list has not been initialized yet. An obvious solution is of course to move some of the offenders to run after the fs_initcall level, but since this might not always be an option, we add a flag "dma_debug_initialized" which is set to false by default, and set to true once dma_debug_init() has had a chance to run. The dma_debug_disabled() helper function previously introduced just needs to check for dma_debug_initialized to allow the caller to proceed or not. Signed-off-by: Florian Fainelli Cc: Dan Williams Cc: Jiri Kosina Cc: Horia Geanta Cc: Brian Norris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/dma-debug.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'lib/dma-debug.c') diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 1ac35dbaf8e0..9722bd2dbc9b 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -102,9 +102,12 @@ static DEFINE_SPINLOCK(free_entries_lock); /* Global disable flag - will be set in case of an error */ static u32 global_disable __read_mostly; +/* Early initialization disable flag, set at the end of dma_debug_init */ +static bool dma_debug_initialized __read_mostly; + static inline bool dma_debug_disabled(void) { - return global_disable; + return global_disable || !dma_debug_initialized; } /* Global error count */ @@ -999,7 +1002,10 @@ void dma_debug_init(u32 num_entries) { int i; - if (dma_debug_disabled()) + /* Do not use dma_debug_initialized here, since we really want to be + * called to set dma_debug_initialized + */ + if (global_disable) return; for (i = 0; i < HASH_SIZE; ++i) { @@ -1026,6 +1032,8 @@ void dma_debug_init(u32 num_entries) nr_total_entries = num_free_entries; + dma_debug_initialized = true; + pr_info("DMA-API: debugging enabled by kernel config\n"); } -- cgit v1.2.2