[mini] Add missing membars when initializing rgctx entries #16904
Conversation
Whenever we are publishing changes to the rgctx arrays, we are racing with rgctx_lazy_fetch_trampoline, so we need to make sure any pointers we set there must have their contents initialized.
BrzVlad
requested review from
lambdageek,
lewurm,
SamMonoRT and
vargaz
as code owners
|
This fixes very random crashes on arm. The offending missing membar is the one needed when storing the newly allocated rgctx_array. This was a little bit confusing because alloc_rgctx_array allocates the array using mono_domain_alloc0 which clears the allocated array and then releases the domain lock, which one can expect to have a release semantic. It turns out in this particular case, we were already holding the domain lock multiple times (doing only a nest decrement) and only the last release has release semantics. |
|
I added the memory barrier outside the allocation because I feel it is the responsibility of the user of the array to add memory barrier if it publishes it to lock free data structures. The allocator just allocates. I wouldn't want to fall on the path of adding memory barriers everywhere, just in case. |
|
Nice work. |
|
@monojenkins backport 2019-08 |
|
@monojenkins squash |
…16909) [2019-08] [mini] Add missing membars when initializing rgctx entries Whenever we are publishing changes to the rgctx arrays, we are racing with rgctx_lazy_fetch_trampoline, so we need to make sure any pointers we set there must have their contents initialized. Backport of #16904. /cc @marek-safar @BrzVlad
…#16904) [mini] Add missing membars when initializing rgctx entries Whenever we are publishing changes to the rgctx arrays, we are racing with rgctx_lazy_fetch_trampoline, so we need to make sure any pointers we set there must have their contents initialized. Commit migrated from mono/mono@b2739b5
Whenever we are publishing changes to the rgctx arrays, we are racing with rgctx_lazy_fetch_trampoline, so we need to make sure any pointers we set there must have their contents initialized.