linux-user: Remove stale "not threadsafe" comments

In linux-user/signal.c we have two FIXME comments claiming that
parts of the signal-handling code are not threadsafe. These are
very old, as they were first introduced in commit 624f7979058
in 2008. Since then we've radically overhauled the signal-handling
logic, while carefully preserving these FIXME comments.

It's unclear exactly what thread-safety issue the original
author was trying to point out -- the relevant data structures
are in the TaskStruct, which makes them per-thread and only
operated on by that thread. The old code at the time of that
commit did have various races involving signal handlers being
invoked at awkward times; possibly this was what was meant.

Delete these FIXME comments:
 * they were written at a time when the way we handled
   signals was completely different
 * the code today appears to us to not have thread-safety issues
 * nobody knows what the problem the comments were trying to
   point out was
so they are serving no useful purpose for us today.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20220114155032.3767771-1-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 0 insertions, 2 deletions

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 27a0ff30e9..2a3f3cc23f 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -999,7 +999,6 @@ int do_sigaction(int sig, const struct target_sigaction *act,
         oact->sa_mask = k->sa_mask;
     }
     if (act) {
-        /* FIXME: This is not threadsafe.  */
         __get_user(k->_sa_handler, &act->_sa_handler);
         __get_user(k->sa_flags, &act->sa_flags);
 #ifdef TARGET_ARCH_HAS_SA_RESTORER
@@ -1149,7 +1148,6 @@ void process_pending_signals(CPUArchState *cpu_env)
     sigset_t *blocked_set;
 
     while (qatomic_read(&ts->signal_pending)) {
-        /* FIXME: This is not threadsafe.  */
         sigfillset(&set);
         sigprocmask(SIG_SETMASK, &set, 0);