Data race detected in libfabric shm provider with multi-threaded client-server setup - Issue#10528

[syskovprdap]

ofiwg/libfabric#10528
*Describe the bug*
When using the shm provider in a simple setup with one client thread and one server thread within a single process, a data race is detected when compiled with clang-19 and run with ThreadSanitizer. The client performs one fi_send, and the server performsone fi_recv, with a message size of 1000 bytes. The data race appears during the fi_cq_read operation on the server side and the fi_send operation on the client side.

*To Reproduce*
1. Set up a process with two threads: one acting as a client and the other as a server.
2. Use the shm provider with libfabric version 1.22.0.
3. Compile the program with clang-19 and enable ThreadSanitizer (-fsanitize=thread).
4. In the client thread, perform an fi_send operation with a message of 1000 bytes.
5. In the server thread, perform an fi_recv operation to receive the message.
Observe that ThreadSanitizer reports a data race during execution

*Expected behavior*
No data race should be detected when performing simple send and receive operations between a client and server thread within the same process using the shm provider.

*Output*
WARNING: ThreadSanitizer: data race (pid=543759)

Server thread:
Read of size 8 at 0x7febb28f3000 by thread T4 (mutexes: write M0, write M1, write M2):
#0 strncmp /home/piotrchmiel/llvm-project/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_common_interceptors.inc:487:3 (test+0x9d66d)
#1 smr_name_compare /home/piotrchmiel/test/third_party/libfabric/prov/shm/src/smr_util.c:351:9 (libfabric.so.1+0xe5a33)

• during cq_read

Client thread:
Previous write of size 8 at 0x7febb28f3000 by main thread:
#0 memcpy /home/piotrchmiel/llvm-project/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_common_interceptors_memintrinsics.inc:115:5 (test+0x8e9de)
#1 smr_send_name /home/piotrchmiel/test/third_party/libfabric/prov/shm/src/smr_ep.c:206:2 (libfabric.so.1+0xdcfcd)

• during fi_send

*Environment:*

• OS (if not Linux), provider, endpoint type, etc.
• Operating System: Ubuntu 22.04
• Compiler: clang-19 with ThreadSanitizer
• libfabric Version: 1.22.0
• Provider: shm
• Endpoint Type: FI_EP_RDM

*Additional context*
The data race occurs specifically on memory access in smr_name_compare (during fi_cq_read on the server side) and in smr_send_name (during fi_send on the client side)