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inspector: more conservative minimum stack size
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PTHREAD_STACK_MIN is 2 KB with musl, which is too small to safely
receive signals. PTHREAD_STACK_MIN + MINSIGSTKSZ is 8 KB on arm64,
which is the musl architecture with the biggest MINSIGSTKSZ so let's
use that as a lower bound and let's quadruple it just in case.

PR-URL: #27855
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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bnoordhuis authored and targos committed Jun 2, 2019
1 parent d948656 commit 89483be
Showing 1 changed file with 13 additions and 6 deletions.
19 changes: 13 additions & 6 deletions src/inspector_agent.cc
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#include <climits> // PTHREAD_STACK_MIN
#endif // __POSIX__

#include <algorithm>
#include <cstring>
#include <sstream>
#include <unordered_map>
Expand Down Expand Up @@ -111,12 +112,18 @@ static int StartDebugSignalHandler() {
CHECK_EQ(0, uv_sem_init(&start_io_thread_semaphore, 0));
pthread_attr_t attr;
CHECK_EQ(0, pthread_attr_init(&attr));
// Don't shrink the thread's stack on FreeBSD. Said platform decided to
// follow the pthreads specification to the letter rather than in spirit:
// https://lists.freebsd.org/pipermail/freebsd-current/2014-March/048885.html
#ifndef __FreeBSD__
CHECK_EQ(0, pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN));
#endif // __FreeBSD__
#if defined(PTHREAD_STACK_MIN) && !defined(__FreeBSD__)
// PTHREAD_STACK_MIN is 2 KB with musl libc, which is too small to safely
// receive signals. PTHREAD_STACK_MIN + MINSIGSTKSZ is 8 KB on arm64, which
// is the musl architecture with the biggest MINSIGSTKSZ so let's use that
// as a lower bound and let's quadruple it just in case. The goal is to avoid
// creating a big 2 or 4 MB address space gap (problematic on 32 bits
// because of fragmentation), not squeeze out every last byte.
// Omitted on FreeBSD because it doesn't seem to like small stacks.
const size_t stack_size = std::max(static_cast<size_t>(4 * 8192),
static_cast<size_t>(PTHREAD_STACK_MIN));
CHECK_EQ(0, pthread_attr_setstacksize(&attr, stack_size));
#endif // defined(PTHREAD_STACK_MIN) && !defined(__FreeBSD__)
CHECK_EQ(0, pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED));
sigset_t sigmask;
// Mask all signals.
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