If the proxyLWP for a thread got a signal just as we were sending the
syscall request to it, then we would end up running the syscall twice.
The fix is to not check the results pipe while sending the syscall request
- wait until we're in a better state for handling signals (the deadlock
the results-read was supposed to avoid cannot actually happen).
Related to that, if we're delivering a signal to a thread, and that thread
is currently waiting for a syscall to complete, make sure we collect the
syscall results before entering the signal handler (otherwise we may end
up bogusly trying to restart the syscall by moving EIP back, even though
it now points to the signal handler rather than the syscall instruction)
This change also adds an assertion to VG_(restart_syscall) to make sure
we were actually restarting a syscall and not just randomly changing EIP
(this found the problem above).
Also, make set/getitimer run in the proxyLWP context, so that they
modify/read the proxyLWP's timers rather than the schedluer LWP's timers.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2013
- restart syscalls which return ERESETARTSYS
- make code to restart a syscall common
- keep a process-wide pending signal set to store as-yet
undelivered signals (only used in 2.4 mode; TODO: siginfo, queues)
- make execve work a bit better - it is impossible to recover from
execve failing, so we try to check that it will before running the
syscall itself (also fixes bug with SuSE 8.2 kernel)
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@1964
a logfile for that pid already exists. This may happen for programs
started during system boot which will tend to get the same pid each boot.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@1928
with the aim of making it more robust, more correct and perhaps faster.
This patch removes the need to poll blocking syscalls, by adding a proxy
LWP for each application thread. This LWP is a kernel thread whose job
is to run all (potentially) blocking syscalls, and also to handle signals.
This allows the kernel to do more of the work of dealing with signals,
so on kernels which do this properly (2.6), Valgrind's behavious is a
lot more posix compliant. On base 2.4 kernels, we emulate some of the
missing 2.6 functionality.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@1918
