[compiler-rt] [ASan] Prevent ASan/LSan deadlock by preloading modules before error reporting (PR #131756)

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git-clang-format --diff 57dc71352c75f88e6819314b2b0e81a62bf285e9 943948f05369c333066b7f04356df82d516dc1ea --extensions cpp -- compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp compiler-rt/lib/asan/asan_report.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/compiler-rt/lib/asan/asan_report.cpp b/compiler-rt/lib/asan/asan_report.cpp
index 8aeb938b2e..b118340d35 100644
--- a/compiler-rt/lib/asan/asan_report.cpp
+++ b/compiler-rt/lib/asan/asan_report.cpp
@@ -126,25 +126,31 @@ class ScopedInErrorReport {
  public:
   explicit ScopedInErrorReport(bool fatal = false)
       : halt_on_error_(fatal || flags()->halt_on_error) {
-   /*
-    * Deadlock Prevention Between ASan and LSan
-    *
-    * Background:
-    * - The `dl_iterate_phdr` function requires holding libdl's internal lock (Lock A).
-    * - LSan acquires the ASan thread registry lock (Lock B) *after* calling `dl_iterate_phdr`.
-    *
-    * Problem Scenario:
-    * When ASan attempts to call `dl_iterate_phdr` while holding Lock B (e.g., during
-    * error reporting via `ErrorDescription::Print`), a circular lock dependency may occur:
-    *   1. Thread 1: Holds Lock B → Requests Lock A (via dl_iterate_phdr)
-    *   2. Thread 2: Holds Lock A → Requests Lock B (via LSan operations)
-    *
-    * Solution:
-    * Proactively load all required modules before acquiring Lock B. This ensures:
-    * 1. Any `dl_iterate_phdr` calls during module loading complete before locking
-    * 2. Subsequent error reporting avoids nested lock acquisition patterns
-    * 3. Eliminates the lock order inversion risk between libdl and ASan's thread registry
-    */
+    /*
+     * Deadlock Prevention Between ASan and LSan
+     *
+     * Background:
+     * - The `dl_iterate_phdr` function requires holding libdl's internal lock
+     * (Lock A).
+     * - LSan acquires the ASan thread registry lock (Lock B) *after* calling
+     * `dl_iterate_phdr`.
+     *
+     * Problem Scenario:
+     * When ASan attempts to call `dl_iterate_phdr` while holding Lock B (e.g.,
+     * during error reporting via `ErrorDescription::Print`), a circular lock
+     * dependency may occur:
+     *   1. Thread 1: Holds Lock B → Requests Lock A (via dl_iterate_phdr)
+     *   2. Thread 2: Holds Lock A → Requests Lock B (via LSan operations)
+     *
+     * Solution:
+     * Proactively load all required modules before acquiring Lock B. This
+     * ensures:
+     * 1. Any `dl_iterate_phdr` calls during module loading complete before
+     * locking
+     * 2. Subsequent error reporting avoids nested lock acquisition patterns
+     * 3. Eliminates the lock order inversion risk between libdl and ASan's
+     * thread registry
+     */
     Symbolizer::GetOrInit()->GetRefreshedListOfModules();
 
     // Make sure the registry and sanitizer report mutexes are locked while

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https://github.com/llvm/llvm-project/pull/131756