From: John Baldwin <jhb@FreeBSD.org>
Date: Mon, 14 Aug 2023 20:38:42 +0000 (-0700)
Subject: fbsd-nat: Fix thread_alive against a running thread.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=57c28d45f9ad14130c8375b3b5ec6996b63574fd;p=binutils-gdb.git

fbsd-nat: Fix thread_alive against a running thread.

FreeBSD's ptrace fails requests with EBUSY against a running process.
Report that the thread is alive instead of dead if ptrace fails with
EBUSY.

This fixes an internal error in the gdb.threads/detach-step-over.exp
test where one process was detached while a thread in a second process
was being stepped.  The core incorrectly assumed the stepping thread
had vanished and discarded the pending stepping state.  When the
thread later reported a SIGTRAP from completing the step, this
triggered an assertion.
---

diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
index d09f4b12bee..5f66a3053d5 100644
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -843,7 +843,13 @@ fbsd_nat_target::thread_alive (ptid_t ptid)
 
       if (ptrace (PT_LWPINFO, ptid.lwp (), (caddr_t) &pl, sizeof pl)
 	  == -1)
-	return false;
+	{
+	  /* EBUSY means the associated process is running which means
+	     the LWP does exist and belongs to a running process.  */
+	  if (errno == EBUSY)
+	    return true;
+	  return false;
+	}
 #ifdef PL_FLAG_EXITED
       if (pl.pl_flags & PL_FLAG_EXITED)
 	return false;