user/sven/linux.git/lib/dma-debug.c, branch v4.1.37

dma-debug: avoid spinlock recursion when disabling dma-debug

2016-06-06T23:12:35Z

[ Upstream commit 3017cd63f26fc655d56875aaf497153ba60e9edf ] With netconsole (at least) the pr_err("... disablingn") call can recurse back into the dma-debug code, where it'll try to grab free_entries_lock again. Avoid the problem by doing the printk after dropping the lock. Link: http://lkml.kernel.org/r/1463678421-18683-1-git-send-email-ville.syrjala@linux.intel.com Signed-off-by: Ville Syrjälä Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

dma-debug: switch check from _text to _stext

2016-02-03T21:23:16Z

[ Upstream commit ea535e418c01837d07b6c94e817540f50bfdadb0 ] In include/asm-generic/sections.h: /* * Usage guidelines: * _text, _data: architecture specific, don't use them in * arch-independent code * [_stext, _etext]: contains .text.* sections, may also contain * .rodata.* * and/or .init.* sections _text is not guaranteed across architectures. Architectures such as ARM may reuse parts which are not actually text and erroneously trigger a bug. Switch to using _stext which is guaranteed to contain text sections. Came out of https://lkml.kernel.org/g/<567B1176.4000106@redhat.com> Signed-off-by: Laura Abbott Reviewed-by: Kees Cook Cc: Russell King Cc: Arnd Bergmann Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

dma-debug: skip debug_dma_assert_idle() when disabled

2015-08-10T19:21:53Z

commit c9d120b0b2b5069cb2ae62f8eac0cef31c8544be upstream. If dma-debug is disabled due to a memory error, DMA unmaps do not affect the dma_active_cacheline radix tree anymore, and debug_dma_assert_idle() can print false warnings. Disable debug_dma_assert_idle() when dma_debug_disabled() is true. Signed-off-by: Haggai Eran Fixes: 0abdd7a81b7e ("dma-debug: introduce debug_dma_assert_idle()") Cc: Dan Williams Cc: Joerg Roedel Cc: Vinod Koul Cc: Russell King Cc: James Bottomley Cc: Florian Fainelli Cc: Sebastian Ott Cc: Jiri Kosina Cc: Horia Geanta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

lib/dma-debug: fix bucket_find_contain()

2015-04-17T13:03:54Z

bucket_find_contain() will search the bucket list for a dma_debug_entry. When the entry isn't found it needs to search other buckets too, since only the start address of a dma range is hashed (which might be in a different bucket). A copy of the dma_debug_entry is used to get the previous hash bucket but when its list is searched the original dma_debug_entry is to be used not its modified copy. This fixes false "device driver tries to sync DMA memory it has not allocated" warnings. Signed-off-by: Sebastian Ott Cc: Florian Fainelli Cc: Horia Geanta Cc: Jiri Kosina Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

dma-debug: prevent early callers from crashing

2014-12-11T01:41:02Z

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

dma-debug: introduce dma_debug_disabled

2014-12-11T01:41:02Z

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

dma-debug: modify check_for_stack output

2014-09-02T12:12:13Z

s/fromstack/from stack Signed-off-by: Horia Geanta Signed-off-by: Jiri Kosina

dma debug: account for cachelines and read-only mappings in overlap tracking

2014-03-04T15:55:47Z

While debug_dma_assert_idle() checks if a given *page* is actively undergoing dma the valid granularity of a dma mapping is a *cacheline*. Sander's testing shows that the warning message "DMA-API: exceeded 7 overlapping mappings of pfn..." is falsely triggering. The test is simply mapping multiple cachelines in a given page. Ultimately we want overlap tracking to be valid as it is a real api violation, so we need to track active mappings by cachelines. Update the active dma tracking to use the page-frame-relative cacheline of the mapping as the key, and update debug_dma_assert_idle() to check for all possible mapped cachelines for a given page. However, the need to track active mappings is only relevant when the dma-mapping is writable by the device. In fact it is fairly standard for read-only mappings to have hundreds or thousands of overlapping mappings at once. Limiting the overlap tracking to writable (!DMA_TO_DEVICE) eliminates this class of false-positive overlap reports. Note, the radix gang lookup is sub-optimal. It would be best if it stopped fetching entries once the search passed a page boundary. Nevertheless, this implementation does not perturb the original net_dma failing case. That is to say the extra overhead does not show up in terms of making the failing case pass due to a timing change. References: http://marc.info/?l=linux-netdev&m=139232263419315&w=2 http://marc.info/?l=linux-netdev&m=139217088107122&w=2 Signed-off-by: Dan Williams Reported-by: Sander Eikelenboom Reported-by: Dave Jones Tested-by: Dave Jones Tested-by: Sander Eikelenboom Cc: Konrad Rzeszutek Wilk Cc: Francois Romieu Cc: Eric Dumazet Cc: Wei Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

dma-debug: fix overlap detection

2014-01-30T00:22:40Z

Commit 0abdd7a81b7e ("dma-debug: introduce debug_dma_assert_idle()") was reworked to expand the overlap counter to the full range expressable by 3 tag bits, but it has a thinko in treating the overlap counter as a pure reference count for the entry. Instead of deleting when the reference-count drops to zero, we need to delete when the overlap-count drops below zero. Also, when detecting overflow we can just test the overlap-count > MAX rather than applying special meaning to 0. Regression report available here: http://marc.info/?l=linux-netdev&m=139073373932386&w=2 This patch, now tested on the original net_dma case, sees the expected handful of reports before the eventual data corruption occurs. Signed-off-by: Dan Williams Reported-by: Sander Eikelenboom Cc: Francois Romieu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

dma-debug: introduce debug_dma_assert_idle()

2014-01-22T00:19:41Z

Record actively mapped pages and provide an api for asserting a given page is dma inactive before execution proceeds. Placing debug_dma_assert_idle() in cow_user_page() flagged the violation of the dma-api in the NET_DMA implementation (see commit 77873803363c "net_dma: mark broken"). The implementation includes the capability to count, in a limited way, repeat mappings of the same page that occur without an intervening unmap. This 'overlap' counter is limited to the few bits of tag space in a radix tree. This mechanism is added to mitigate false negative cases where, for example, a page is dma mapped twice and debug_dma_assert_idle() is called after the page is un-mapped once. Signed-off-by: Dan Williams Cc: Joerg Roedel Cc: Vinod Koul Cc: Russell King Cc: James Bottomley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds