i#3049: clean postcall_cache when drwrap_exit #3064
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This commit is the supplement for PR DynamoRIO#3050. We also need to clean postcall_cache on drwrap_exit, otherwise post_callback will not be invoked at re-attach. This is because the registration of post_callback relies on pre_callback, and the pre_callback checks postcall_cache before registering the post_callback. The stale data in postcall_cache prevents post_callback being registered to the hash table. Fixes DynamoRIO#3049
Add var declaration to fix build. Fixes DynamoRIO#3049
ext/drwrap/drwrap.c
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| @@ -970,7 +970,7 @@ void | |||
| drwrap_exit(void) | |||
| { | |||
| /* handle multiple sets of init/exit calls */ | |||
| int count = dr_atomic_add32_return_sum(&drwrap_init_count, -1); | |||
| int i, count = dr_atomic_add32_return_sum(&drwrap_init_count, -1); | |||
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Please declare i on a separate line: I find this harder to read
ext/drwrap/drwrap.c
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| @@ -981,6 +981,11 @@ drwrap_exit(void) | |||
| !dr_unregister_delete_event(drwrap_fragment_delete)) | |||
| ASSERT(false, "failed to unregister in drwrap_exit"); | |||
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| for (i = 0; i < POSTCALL_CACHE_SIZE; i++) { | |||
| postcall_cache[i] = NULL; | |||
| } | |||
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This is fine for this CL but it brings up two thoughts:
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For large data structures zeroing at exit is costly when there's no chance or re-attach: which is all of the time for regular non-static DR. Inside DR we only zero for doing_detach. We may want to export that for extensions.
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We should add a re-attach test for drwrap.
I filed #3065 for this, split from #2157. Let's reference both issues in the merge commit message.
Move `i` declaration inside for loop Fixes DynamoRIO#3049, DynamoRIO#3065
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This commit is a supplement for PR #3050.
We need to clean
postcall_cacheondrwrap_exitas well, otherwisepost-callback (one of the arguments when calling
drwrap_wrap_ex) will not be invoked at re-attach. This is because the registration of post-callback relies on pre-callback, and pre-callback checks postcall-cache before registering the post-callback. Stale data inpostcall_cacheprevents post-callback being registered to the hash table.Fixes #3049