is bcc object initialization thread-safe #4500
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Could you try the following diff ? diff --git a/src/cc/frontends/clang/b_frontend_action.cc b/src/cc/frontends/clang/b_frontend_action.cc
index e9c83a96..0e27753f 100644
--- a/src/cc/frontends/clang/b_frontend_action.cc
+++ b/src/cc/frontends/clang/b_frontend_action.cc
@@ -123,17 +123,8 @@ const char *pt_regs_syscall_regs(void) {
return calling_conv_regs[0];
}
-/* Use resolver only once per translation */
-static void *kresolver = NULL;
-static void *get_symbol_resolver(void) {
- if (!kresolver)
- kresolver = bcc_symcache_new(-1, nullptr);
- return kresolver;
-}
-
-static std::string check_bpf_probe_read_kernel(void) {
+static std::string check_bpf_probe_read_kernel(void *resolver) {
bool is_probe_read_kernel;
- void *resolver = get_symbol_resolver();
uint64_t addr = 0;
is_probe_read_kernel = bcc_symcache_resolve_name(resolver, nullptr,
"bpf_probe_read_kernel", &addr) >= 0 ? true: false;
@@ -147,11 +138,10 @@ static std::string check_bpf_probe_read_kernel(void) {
}
static std::string check_bpf_probe_read_user(llvm::StringRef probe,
- bool& overlap_addr) {
+ bool& overlap_addr, void *resolver) {
if (probe.str() == "bpf_probe_read_user" ||
probe.str() == "bpf_probe_read_user_str") {
// Check for probe_user symbols in backported kernel before fallback
- void *resolver = get_symbol_resolver();
uint64_t addr = 0;
bool found = bcc_symcache_resolve_name(resolver, nullptr,
"bpf_probe_read_user", &addr) >= 0 ? true: false;
@@ -1176,7 +1166,7 @@ bool BTypeVisitor::VisitCallExpr(CallExpr *Call) {
// space arch.
bool overlap_addr = false;
std::string probe = check_bpf_probe_read_user(Decl->getName(),
- overlap_addr);
+ overlap_addr, fe_.get_resolver());
if (overlap_addr) {
error(GET_BEGINLOC(Call), "bpf_probe_read_user not found. Use latest kernel");
return false;
@@ -1232,7 +1222,7 @@ bool BTypeVisitor::VisitCallExpr(CallExpr *Call) {
bool overlap_addr = false;
text += check_bpf_probe_read_user(StringRef("bpf_probe_read_user"),
- overlap_addr);
+ overlap_addr, fe_.get_resolver());
if (overlap_addr) {
error(GET_BEGINLOC(Call), "bpf_probe_read_user not found. Use latest kernel");
return false;
@@ -1751,7 +1741,20 @@ BFrontendAction::BFrontendAction(
mod_src_(mod_src),
next_fake_fd_(-1),
fake_fd_map_(fake_fd_map),
- perf_events_(perf_events) {}
+ perf_events_(perf_events),
+ resolver(nullptr) {}
+
+void *BFrontendAction::get_resolver() {
+ if (!resolver)
+ resolver = bcc_symcache_new(-1, nullptr);
+ return resolver;
+}
+
+BFrontendAction::~BFrontendAction() {
+ if (resolver) {
+ bcc_free_symcache(resolver, -1);
+ }
+}
bool BFrontendAction::is_rewritable_ext_func(FunctionDecl *D) {
StringRef file_name = rewriter_->getSourceMgr().getFilename(GET_BEGINLOC(D));
@@ -1766,11 +1769,7 @@ void BFrontendAction::DoMiscWorkAround() {
// to guard certain fields. The workaround here intends to define
// CONFIG_CC_STACKPROTECTOR properly based on other configs, so it relieved any bpf
// program (using task_struct, etc.) of patching the below code.
- std::string probefunc = check_bpf_probe_read_kernel();
- if (kresolver) {
- bcc_free_symcache(kresolver, -1);
- kresolver = NULL;
- }
+ std::string probefunc = check_bpf_probe_read_kernel(resolver);
if (probefunc == "bpf_probe_read") {
probefunc = "#define bpf_probe_read_kernel bpf_probe_read\n"
"#define bpf_probe_read_kernel_str bpf_probe_read_str\n"
diff --git a/src/cc/frontends/clang/b_frontend_action.h b/src/cc/frontends/clang/b_frontend_action.h
index c2881d60..48fa583a 100644
--- a/src/cc/frontends/clang/b_frontend_action.h
+++ b/src/cc/frontends/clang/b_frontend_action.h
@@ -159,6 +159,7 @@ class BFrontendAction : public clang::ASTFrontendAction {
ProgFuncInfo &prog_func_info, std::string &mod_src,
const std::string &maps_ns, fake_fd_map_def &fake_fd_map,
std::map<std::string, std::vector<std::string>> &perf_events);
+ ~BFrontendAction();
// Called by clang when the AST has been completed, here the output stream
// will be flushed.
@@ -180,6 +181,7 @@ class BFrontendAction : public clang::ASTFrontendAction {
std::string> map_def) {
fake_fd_map_[fd] = move(map_def);
}
+ void *get_resolver();
private:
llvm::raw_ostream &os_;
@@ -197,6 +199,7 @@ class BFrontendAction : public clang::ASTFrontendAction {
int next_fake_fd_;
fake_fd_map_def &fake_fd_map_;
std::map<std::string, std::vector<std::string>> &perf_events_;
+ void *resolver;
};
} // namespace visitor |
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I imported the diff file into the local code, recompiled and installed bcc, and tested it again without any core dump. However, there is still a problem with header file not found when multiple |
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Different errors occur when a process compiles ebpf concurrently using bcc。
e.g.
Sometimes a coredump occurs.
demo.cpp
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