From: Ken Brown <kbrown@cornell.edu>
To: cygwin-patches@cygwin.com
Subject: [PATCH 1/8] Cygwin: FIFO: lock fixes
Date: Tue, 4 Aug 2020 08:55:00 -0400 [thread overview]
Message-ID: <20200804125507.8842-2-kbrown@cornell.edu> (raw)
In-Reply-To: <20200804125507.8842-1-kbrown@cornell.edu>
Add some missing locks and remove one extra unlock. Clarify for some
functions whether caller or callee acquires lock, and add appropriate
comments.
---
winsup/cygwin/fhandler_fifo.cc | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index e9d0187d4..ee7f47c0c 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -316,6 +316,7 @@ fhandler_fifo::wait_open_pipe (HANDLE& ph)
return status;
}
+/* Always called with fifo_client_lock in place. */
int
fhandler_fifo::add_client_handler (bool new_pipe_instance)
{
@@ -345,6 +346,7 @@ fhandler_fifo::add_client_handler (bool new_pipe_instance)
return 0;
}
+/* Always called with fifo_client_lock in place. */
void
fhandler_fifo::delete_client_handler (int i)
{
@@ -354,7 +356,8 @@ fhandler_fifo::delete_client_handler (int i)
(nhandlers - i) * sizeof (fc_handler[i]));
}
-/* Delete handlers that we will never read from. */
+/* Delete handlers that we will never read from. Always called with
+ fifo_client_lock in place. */
void
fhandler_fifo::cleanup_handlers ()
{
@@ -369,6 +372,7 @@ fhandler_fifo::cleanup_handlers ()
}
}
+/* Always called with fifo_client_lock in place. */
void
fhandler_fifo::record_connection (fifo_client_handler& fc,
fifo_client_connect_state s)
@@ -398,6 +402,7 @@ fhandler_fifo::update_my_handlers ()
if (!prev_proc)
api_fatal ("Can't open process of previous owner, %E");
+ fifo_client_lock ();
for (int i = 0; i < get_shared_nhandlers (); i++)
{
if (add_client_handler (false) < 0)
@@ -419,10 +424,12 @@ fhandler_fifo::update_my_handlers ()
fc.last_read = shared_fc_handler[i].last_read;
}
}
+ fifo_client_unlock ();
set_prev_owner (null_fr_id);
return ret;
}
+/* Always called with fifo_client_lock and owner_lock in place. */
int
fhandler_fifo::update_shared_handlers ()
{
@@ -435,9 +442,7 @@ fhandler_fifo::update_shared_handlers ()
set_shared_nhandlers (nhandlers);
memcpy (shared_fc_handler, fc_handler, nhandlers * sizeof (fc_handler[0]));
shared_fc_handler_updated (true);
- owner_lock ();
set_prev_owner (me);
- owner_unlock ();
return 0;
}
@@ -509,7 +514,6 @@ fhandler_fifo::fifo_reader_thread_func ()
if (update_my_handlers () < 0)
debug_printf ("error updating my handlers, %E");
owner_found ();
- owner_unlock ();
/* Fall through to owner_listen. */
}
}
@@ -602,8 +606,13 @@ owner_listen:
}
if (ph)
NtClose (ph);
- if (update && update_shared_handlers () < 0)
- api_fatal ("Can't update shared handlers, %E");
+ if (update)
+ {
+ owner_lock ();
+ if (get_owner () == me && update_shared_handlers () < 0)
+ api_fatal ("Can't update shared handlers, %E");
+ owner_unlock ();
+ }
fifo_client_unlock ();
if (cancel)
goto canceled;
@@ -1402,9 +1411,11 @@ fhandler_fifo::fstatvfs (struct statvfs *sfs)
void
fhandler_fifo::close_all_handlers ()
{
+ fifo_client_lock ();
for (int i = 0; i < nhandlers; i++)
fc_handler[i].close ();
nhandlers = 0;
+ fifo_client_unlock ();
}
fifo_client_connect_state
--
2.28.0
next prev parent reply other threads:[~2020-08-04 12:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-04 12:54 [PATCH 0/8] FIFO: bug fixes and small improvements Ken Brown
2020-08-04 12:55 ` Ken Brown [this message]
2020-08-04 12:55 ` [PATCH 2/8] Cygwin: FIFO: fix timing issue with owner change Ken Brown
2020-08-04 12:55 ` [PATCH 3/8] Cygwin: FIFO: add a timeout to take_ownership Ken Brown
2020-08-04 12:55 ` [PATCH 4/8] Cygwin: FIFO: reorganize some fifo_client_handler methods Ken Brown
2020-08-04 12:55 ` [PATCH 5/8] Cygwin: FIFO: don't read from pipes that are closing Ken Brown
2020-08-04 12:55 ` [PATCH 6/8] Cygwin: FIFO: synchronize the fifo_reader and fifosel threads Ken Brown
2020-08-04 12:55 ` [PATCH 7/8] Cygwin: FIFO: fix indentation Ken Brown
2020-08-04 12:55 ` [PATCH 8/8] Cygwin: FIFO: add a third pass to raw_read Ken Brown
2020-08-04 15:04 ` [PATCH 0/8] FIFO: bug fixes and small improvements Corinna Vinschen
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