A number of ztest functions create one or more 312B ztest_od_t data
structures. To conserve stack usage, this commit moves all of these data
structures to the heap. However, I am still seeing ztest segfaults due
to heavy stack usage of the dbuf_findbp() -> dbuf_hold_impl() recursion.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This check is part of ztest and a memory failure here is unlikely.
However, if this does occur simply exiting is an perfectly valid
way to handle the issue and it resulves the compiler warning.
ztest.c:5522: error: ignoring return value of 'asprintf',
declared with attribute warn_unused_result
While ztest does run in user space we run it with the same stack
restrictions it would have in kernel space. This ensures that any
stack related issues which would be hit in the kernel can be caught
and debugged in user space instead.
This patch is a first pass to limit the stack usage of every ztest
function to 1024 bytes. Subsequent updates can further reduce this
There are 3 fixes in thie commit. First, update ztest_run() to store
the thread id and not the address of the kthread_t. This will be freed
on thread exit and is not safe to use. This is pretty close to how
things were done in the original ztest code before I got there.
Second, for extra paranoia update thread_exit() to return a special
TS_MAGIC value via pthread_exit(). This value is then verified in
pthread_join() to ensure the thread exited cleanly. This can be
done cleanly because the kthread doesn't provide a return code
mechanism we need to worry about.
Third, replace the ztest deadman thread with a signal handler. We
cannot use the previous approach because the correct behavior for
pthreads is to wait for all threads to exit before terminating the
process. Since the deadman thread won't call exit by design we
end up hanging in kernel_exit(). To avoid this we just setup a
SIGALRM signal handle and register a deadman alarm. IMHO this
is simpler and cleaner anyway.
This is a portability change which removes the dependence of the Solaris
thread library. All locations where Solaris thread API was used before
have been replaced with equivilant Solaris kernel style thread calls.
In user space the kernel style threading API is implemented in term of
the portable pthreads library. This includes all threads, mutexs,
condition variables, reader/writer locks, and taskqs.
Under FC11 rpm builds by default add the --fortify-source option which
ensures that functions flagged with certain attributes must have their
return codes checked. Normally this is just a warning but we always
build with -Werror so this is fatal. Simply wrap the function in a
verify call to ensure we catch a failure if there is one.
within an ASSERT with the ASSERTV macro which will ensure it will
be removed when the ASSERTs are commented out. This makes gcc much
happier, makes the variables usage explicit, and removes the need
for the compiler to detect it is unused and do the right thing.
Most of these fixes appear to be harmless and should never occur.
However, there were a few cases in this patch which do concern me,
I doubt we're seeing them but they look possible... mainly in the
user tools.
Brian Behlendorf
Ned Bass
Ricardo M. Correia