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[mempool] Annotate functions for clang's ThreadSanitizer #5191

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Merged
lewurm merged 3 commits into from
Jul 21, 2017
Merged

[mempool] Annotate functions for clang's ThreadSanitizer #5191

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4da608a
[mempool] Annotate functions for ThreadSanitizer
cherusker Jul 8, 2017
d457bc6
[fixup!] Test the NO_SANITIZE_THREAD macro
cherusker Jul 8, 2017
bb10fdc
[fixup!] Merge comments / documentation
cherusker Jul 11, 2017
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31 changes: 31 additions & 0 deletions mono/metadata/mempool.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@

#include "mempool.h"
#include "mempool-internals.h"
#include "utils/mono-compiler.h"

/*
* MonoMemPool is for fast allocation of memory. We free
Expand Down Expand Up @@ -92,9 +93,19 @@ mono_mempool_new (void)

/**
* mono_mempool_new_size:
*
* clang's ThreadSanitizer detects races of total_bytes_allocated and pool->d.allocated throughout the functions
* * mono_mempool_alloc
* * mono_mempool_new_size
* * mono_mempool_destroy
* while these races could lead to wrong values, total_bytes_allocated is just used for debugging / reporting and since
* the mempool.c functions are called quite often, a discussion led the the conclusion of ignoring these races:
* https://bugzilla.xamarin.com/show_bug.cgi?id=57936
*
* \param initial_size the amount of memory to initially reserve for the memory pool.
* \returns a new memory pool with a specific initial memory reservation.
*/
MONO_NO_SANITIZE_THREAD
MonoMemPool *
mono_mempool_new_size (int initial_size)
{
Expand All @@ -120,10 +131,20 @@ mono_mempool_new_size (int initial_size)

/**
* mono_mempool_destroy:
*
* clang's ThreadSanitizer detects races of total_bytes_allocated and pool->d.allocated throughout the functions
* * mono_mempool_alloc
* * mono_mempool_new_size
* * mono_mempool_destroy
* while these races could lead to wrong values, total_bytes_allocated is just used for debugging / reporting and since
* the mempool.c functions are called quite often, a discussion led the the conclusion of ignoring these races:
* https://bugzilla.xamarin.com/show_bug.cgi?id=57936
*
* \param pool the memory pool to destroy
*
* Free all memory associated with this pool.
*/
MONO_NO_SANITIZE_THREAD
void
mono_mempool_destroy (MonoMemPool *pool)
{
Expand Down Expand Up @@ -251,13 +272,23 @@ get_next_size (MonoMemPool *pool, int size)

/**
* mono_mempool_alloc:
*
* clang's ThreadSanitizer detects races of total_bytes_allocated and pool->d.allocated throughout the functions
* * mono_mempool_alloc
* * mono_mempool_new_size
* * mono_mempool_destroy
* while these races could lead to wrong values, total_bytes_allocated is just used for debugging / reporting and since
* the mempool.c functions are called quite often, a discussion led the the conclusion of ignoring these races:
* https://bugzilla.xamarin.com/show_bug.cgi?id=57936
*
* \param pool the memory pool to use
* \param size size of the memory block
*
* Allocates a new block of memory in \p pool .
*
* \returns the address of a newly allocated memory block.
*/
MONO_NO_SANITIZE_THREAD
gpointer
mono_mempool_alloc (MonoMemPool *pool, guint size)
{
Expand Down
11 changes: 11 additions & 0 deletions mono/utils/mono-compiler.h
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Expand Up @@ -113,5 +113,16 @@ typedef SSIZE_T ssize_t;
#define MONO_GNUC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
#endif

/* Used to tell clang's ThreadSanitizer to not report data races that occur within a certain function */
#if defined(__has_feature)
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@alexrp alexrp Jul 9, 2017 •
edited
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Could we factor this into a separate macro? Like so:

#if defined (__has_feature)
#define MONO_CLANG_HAS_FEATURE (...) (__has_feature (__VA_ARGS__))
#else
#define MONO_CLANG_HAS_FEATURE (...) (FALSE)
#endif

#if MONO_CLANG_HAS_FEATURE (thread_sanitizer)
#define MONO_NO_SANITIZE_THREAD __attribute__ ((no_sanitize ("thread")))
#else
#define MONO_NO_SANITIZE_THREAD
#endif

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@vargaz vargaz Jul 9, 2017

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I'd prefer having a simple macro, not a magic one.

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@cherusker cherusker Jul 9, 2017

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@vargaz are you for or against @alexrp's idea? Generally non of the two versions look too magical to me - the current one is more compact (IMO), the idea of @alexrp has a better reusability which will come handy when working with other clang features in the future - generally I'm tempted to use what @alexrp suggested :)

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@vargaz vargaz Jul 9, 2017

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I like the simple version.

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@cherusker cherusker Jul 11, 2017

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I would suggest to leave it as it is for this PR but definitely think about expanding the macro, once more checkers are added that rely on __has_feature.

#if __has_feature(thread_sanitizer)
#define MONO_NO_SANITIZE_THREAD __attribute__ ((no_sanitize("thread")))
#else
#define MONO_NO_SANITIZE_THREAD
#endif
#else
#define MONO_NO_SANITIZE_THREAD
#endif

#endif /* __UTILS_MONO_COMPILER_H__*/