Commit Graph

3 Commits

Author SHA1 Message Date
Kostya Kortchinsky 3ad32a037e [scudo] Correct a behavior on the shared TSD registry
Summary:
There is an error in the shared TSD registry logic when looking for a
TSD in the slow path. There is an unlikely event when a TSD's precedence
was 0 after attempting a `tryLock` which indicated that it was grabbed
by another thread in between. We dealt with that case by continuing to
the next iteration, but that meant that the `Index` was not increased
and we ended up trying to lock the same TSD.
This would manifest in heavy contention, and in the end we would still
lock a TSD, but that was a wasted iteration.
So, do not `continue`, just skip the TSD as a potential candidate.

This is in both the standalone & non-standalone versions.

Reviewers: morehouse, eugenis, vitalybuka, hctim

Reviewed By: morehouse

Subscribers: delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D63783

llvm-svn: 364345
2019-06-25 19:58:11 +00:00
Kostya Kortchinsky 624a24e156 [scudo][standalone] Unmap memory in tests
Summary:
The more tests are added, the more we are limited by the size of the
address space on 32-bit. Implement `unmapTestOnly` all around (like it
is in sanitzer_common) to be able to free up some memory.
This is not intended to be a proper "destructor" for an allocator, but
allows us to not fail due to having no memory left.

Reviewers: morehouse, vitalybuka, eugenis, hctim

Reviewed By: morehouse

Subscribers: delcypher, jfb, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D63146

llvm-svn: 363095
2019-06-11 19:50:12 +00:00
Kostya Kortchinsky 52bfd673d1 [scudo][standalone] Introduce the thread specific data structures
Summary:
This CL adds the structures dealing with thread specific data for the
allocator. This includes the thread specific data structure itself and
two registries for said structures: an exclusive one, where each thread
will have its own TSD struct, and a shared one, where a pool of TSD
structs will be shared by all threads, with dynamic reassignment at
runtime based on contention.

This departs from the current Scudo implementation: we intend to make
the Registry a template parameter of the allocator (as opposed to a
single global entity), allowing various allocators to coexist with
different TSD registry models. As a result, TSD registry and Allocator
are tightly coupled.

This also corrects a couple of things in other files that I noticed
while adding this.

Reviewers: eugenis, vitalybuka, morehouse, hctim

Reviewed By: morehouse

Subscribers: srhines, mgorny, delcypher, jfb, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D62258

llvm-svn: 362962
2019-06-10 16:50:52 +00:00