When using pr_err in signal handler, locking is used
in an unsafe manner. If another signal happens while holding the
lock, deadlock can happen.
To fix this, we can introduce mutex_trylock similar to
pthread_mutex_trylock that returns immediately. Due to the fact
that lock is used only for writing first_err, this change garantees
that deadlock cannot happen.
Fixes: #358
Signed-off-by: Ivan Pravdin <ipravdin.official@gmail.com>
The clang analyzer, scan-build, cannot correctly handle the
LOCK_BUG_ON() macro. At multiple places there is the following warning:
Error: CLANG_WARNING:
criu/pie/restorer.c:1221:4: warning: Dereference of null pointer
include/common/lock.h:14:35: note: expanded from macro 'LOCK_BUG_ON'
*(volatile unsigned long *)NULL = 0xdead0000 + __LINE__
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
This just disable the clang analyzer for the LOCK_BUG_ON() macro.
Signed-off-by: Adrian Reber <areber@redhat.com>
Real syscalls generation is inside criu for a while
but will be moved out in the next patch.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
The idea is symilar to kernel's wake_up() and wait_event().
One task needs some event. It checks the event has not
happened yet (fle hasn't received, unix peer hasn't bound, etc)
and calls get_fds_event(). Other task makes the event
(sends a fle, binds the peer to a name, etc) and calls set_fds_event().
So, while there is no an event, the first task is sleeping,
and the second wakes it up later:
Task A: clear_fds_event();
if (!socket_bound)
wait_fds_event(); /* sleep */
Task B: bind_socket();
set_fds_event(); /* wake up */
For the details of using see next patches.
v5: Use bit operations.
Split clear_fds_event from wait function.
v2: Do not wait for foreign transport sock is ready,
as it's guarantied by we create it before CR_STATE_FORKING.
travis-ci: success for Rework file opening scheme to make it asynchronous (rev5)
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
System call sys_futex() requires that (from futex(2)):
"On all platforms, futexes are four-byte integers
that must be aligned on a four-byte boundary".
travis-ci: success for locks: Mask futexes aligned
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
