[PATCH] D73055: [scudo][standalone] Allow sched_getaffinity to fail

[Kostya Kortchinsky via Phabricator via llvm-commits]

cryptoad created this revision.
cryptoad added reviewers: cferris, eugenis, hctim, morehouse, pcc.
Herald added projects: Sanitizers, LLVM.
Herald added a subscriber: Sanitizers.

In some configuration, `sched_getaffinity` can fail. Some reasons for
that being the lack of `CAP_SYS_NICE` capability or some syscall
filtering and so on.

This should not be fatal to the allocator, so in this situation, we
will fallback to the `MaxTSDCount` value specified in the allocator
configuration.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D73055

Files:
  compiler-rt/lib/scudo/standalone/linux.cpp
  compiler-rt/lib/scudo/standalone/tsd_shared.h


Index: compiler-rt/lib/scudo/standalone/tsd_shared.h
===================================================================
--- compiler-rt/lib/scudo/standalone/tsd_shared.h
+++ compiler-rt/lib/scudo/standalone/tsd_shared.h
@@ -18,7 +18,9 @@
   void initLinkerInitialized(Allocator *Instance) {
     Instance->initLinkerInitialized();
     CHECK_EQ(pthread_key_create(&PThreadKey, nullptr), 0); // For non-TLS
-    NumberOfTSDs = Min(Max(1U, getNumberOfCPUs()), MaxTSDCount);
+    const u32 NumberOfCPUs = getNumberOfCPUs();
+    NumberOfTSDs =
+        (NumberOfCPUs == 0) ? MaxTSDCount : Min(NumberOfCPUs, MaxTSDCount);
     TSDs = reinterpret_cast<TSD<Allocator> *>(
         map(nullptr, sizeof(TSD<Allocator>) * NumberOfTSDs, "scudo:tsd"));
     for (u32 I = 0; I < NumberOfTSDs; I++)
Index: compiler-rt/lib/scudo/standalone/linux.cpp
===================================================================
--- compiler-rt/lib/scudo/standalone/linux.cpp
+++ compiler-rt/lib/scudo/standalone/linux.cpp
@@ -130,9 +130,12 @@
          static_cast<u64>(TS.tv_nsec);
 }
 
+// sched_getaffinity can fail (no CAP_SYS_NICE, syscall filtering, etc), in
+// which case the function shall return 0.
 u32 getNumberOfCPUs() {
   cpu_set_t CPUs;
-  CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
+  if (sched_getaffinity(0, sizeof(cpu_set_t), &CPUs) != 0)
+    return 0;
   return static_cast<u32>(CPU_COUNT(&CPUs));
 }
 


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