Up until now no SPL consumer attempted to perform signed 64-bit
division so there was no need to support this. That has now
changed so I adding 64-bit division support for 32-bit platforms.
The signed implementation is based on the unsigned version.
Since the have been several bug reports in the past concerning
correct 64-bit division on 32-bit platforms I added some long
over due regression tests. Much to my surprise the unsigned
64-bit division regression tests failed.
This was surprising because __udivdi3() was implemented by simply
calling div64_u64() which is provided by the kernel. This meant
that the linux kernels 64-bit division algorithm on 32-bit platforms
was flawed. After some investigation this turned out to be exactly
the case.
Because of this I was forced to abandon the kernel helper and
instead to fully implement 64-bit division in the spl. There are
several published implementation out there on how to do this
properly and I settled on one proposed in the book Hacker's Delight.
Their proposed algoritm is freely available without restriction
and I have just modified it to be linux kernel friendly.
The update implementation now passed all the unsigned and signed
regression tests. This should be functional, but not fast, which is
good enough for out purposes. If you want fast too I'd strongly
suggest you upgrade to a 64-bit platform. I have also reported the
kernel bug and we'll see if we can't get it fixed up stream.
For some reason when awk invoked by the usermode helper the command
always fails. Interestingly gawk does not suffer from this problem
which is why I never observed this failure since the distro I tested
with all had gawk installed instead of awk. Anyway, the simplest
thing to do here is to just make gawk mandatory. I've added a
configure check for gawk specifically and have updated the command
to call gawk not awk.
I didn't notice at the time but user_path_dir() was not introduced
at the same time as set_fs_pwd() change. I had lumped the two
together but in fact user_path_dir() was introduced in 2.6.27 and
set_fs_pwd() taking 2 args was introduced in 2.6.25. This means
builds against 2.6.25-2.6.26 kernels were broken.
To fix this I've added a check for user_path_dir() and no longer
assume that if set_fs_pwd() takes 2 args then user_path_dir() is
also available.
Use 3 threads and 8 tasks. Dispatch the final 3 tasks with TQ_FRONT.
The first three tasks keep the worker threads busy while we stuff the
queues. Use msleep() to force a known execution order, assuming
TQ_FRONT is properly honored. Verify that the expected completion
order occurs.
The splat_taskq_test5_order() function may be useful in more than
one test. This commit generalizes it by renaming the function to
splat_taskq_test_order() and adding a name argument instead of
assuming SPLAT_TASKQ_TEST5_NAME as the test name.
The documentation for splat taskq regression test #5 swaps the two required
completion orders in the diagram. This commit corrects the error.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
On open() and initialize the buffer with the SPL version string. The
user space splat utility expects to find the SPL version string when
it opens and reads from /dev/splatctl.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Adds a task queue to receive tasks dispatched with TQ_FRONT. Worker
threads pull tasks from this high priority queue before the default
pending queue.
Executing tasks out of FIFO order potentially breaks taskq_lowest_id()
if we do not preserve the ordering of the work list by taskqid.
Therefore, instead of always appending to the work list, we search for
the appropriate place to insert a task. The common case is to append
to the list, so we make this operation efficient by searching the work
list in reverse order.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
As of linux-2.6.33 the ctl_name member of the ctl_table struct
has been entirely removed. The upstream code has been updated
to depend entirely on the the procname member. To handle this
all references to ctl_name are wrapped in a CTL_NAME macro which
simply expands to nothing for newer kernels. Older kernels are
supported by having it expand to .ctl_name = X just as before.
When HAVE_MUTEX_OWNER is defined and we are directly accessing
mutex->owner treat is as volative with the ACCESS_ONCE() helper.
Without this you may get a stale cached value when accessing it
from different cpus. This can result in incorrect behavior from
mutex_owned() and mutex_owner(). This is not a problem for the
!HAVE_MUTEX_OWNER case because in this case all the accesses
are covered by a spin lock which similarly gaurentees we will
not be accessing stale data.
Secondly, check CONFIG_SMP before allowing access to mutex->owner.
I see that for non-SMP setups the kernel does not track the owner
so we cannot rely on it.
Thirdly, check CONFIG_MUTEX_DEBUG when this is defined and the
HAVE_MUTEX_OWNER is defined surprisingly the mutex->owner will
not be cleared on mutex_exit(). When this is the case the SPL
needs to make sure to do it to ensure MUTEX_HELD() behaves as
expected or you will certainly assert in mutex_destroy().
Finally, improve the mutex regression tests. For mutex_owned() we
now minimally check that it behaves correctly when checked from the
owner thread or the non-owner thread. This subtle behaviour has bit
me before and I'd like to catch it early next time if it reappears.
As for mutex_owned() regression test additonally verify that
mutex->owner is always cleared on mutex_exit().
The call to wake_up() must be moved under the spin lock because
once we drop the lock 'tp' may no longer be valid because the
creating thread has exited. This basic thread implementation
was correct, this was simply a flaw in the test case.
We might as well have both asprintf() variants. This allows us
to safely pass a va_list through several levels of the stack
using va_copy() instead of va_start().
This fix was long overdue. Most of the ground work was laid long
ago to include the exact function and line number in the error message
which there was an issue with a memory allocation call. However,
probably due to lack of time at the moment that informatin never
made it in to the error message. This patch fixes that and trys
to standardize the kmem debug messages as well.
This patch adds three missing Solaris functions: kmem_asprintf(), strfree(),
and strdup(). They are all implemented as a thin layer which just calls
their Linux counterparts. As part of this an autoconf check for kvasprintf
was added because it does not appear in older kernels. If the kernel does
not provide it then spl-generic implements it.
Additionally the dead DEBUG_KMEM_UNIMPLEMENTED code was removed to clean
things up and make the kmem.h a little more readable.
Under linux the proc.h header is for the /proc filesystem, and under
Solaris the proc/h header if for processes. This patch correctly
moves the Linux proc functionality in a linux/proc_compat.h header
and leaves the sys/proc.h for use by Solaris. Minor updates were
required to all the call sites where it was included of course.
Running 'zpool create' on a 32-bit machine with an SPL compiled with
gcc 4.4.4 led to a stack overlow. This turned out to be due to some
sort of 'optimization' by gcc:
uint64_t __umoddi3(uint64_t dividend, uint64_t divisor)
{
return dividend - divisor * (dividend / divisor);
}
This code was supposed to be using __udivdi3 to implement /, but gcc
instead implemented it via __umoddi3 itself.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Remove RW_COUNT() from the rwlock implementation. The idea was that it
could be used as a generic wrapper for getting at the internal state
of a rwlock. While a good idea it's proven problematic to keep it
correct for multiple archs and internal implementation changes. In
short it hasn't been worth the trouble.
With that and simplicity in mind things have been updated to use the
rwsem_is_locked() function instead of RW_COUNT for the RW_*_HELD()
functions. As for rw_upgrade() it remains only implemented for
the generic rwsem implemenation. It remains to be determined if its
worth the effort of adding a custom implementation for each arch.
While I may prefer to have the system panic on an SBUG and to get
crash dump for analysis. I suspect most peoples systems are not
configured from crash dump and the best thing to so is to simply
halt the thread and print an error to the console. This way they
have a good chance of actually saving the stack trace and debug log.
Remove the kmem_set_warning() hack used by the kmem-splat regression
tests with a per-allocation flag called __GFP_NOWARN. This matches
the lower level linux flag of similar by slightly different function.
The idea is you can then explicitly set this flag on requests where
you know your breaking the max 8k rule but you need/want to do it
anyway.
This is currently used by the regression tests where we intentionally
push things to the limit but don't want the log noise. Additionally,
we are forced to use it in spl_kmem_cache_create() because by default
NR_CPUS is very large and theres no easy way to handle that.
Finally, I've added a stack_dump() call to the warning when it is
trigger to make to clear exactly where the allocation is taking place.
Using /tmp/ is a preferable default, it can always be overriden
using the module option on a case-by-case basis.
Additionally standardize some log messages based on the same
default log level used by the kernel.
Updated AUTHORS, COPYING, DISCLAIMER, and INSTALL files. Added
standardized headers to all source file to clearly indicate the
copyright, license, and to give credit where credit is due.
While this does incur slightly more overhead we should be using
do_posix_clock_monotonic_gettime() for gethrtime() as described
by the existing comment.
This is a minor extension to the condition variable API to allow
for reasonable signal handling on Linux. The cv_wait() function by
definition must wait unconditionally for cv_signal()/cv_broadcast()
before waking it. This makes it impossible to woken by a signal
such as SIGTERM. The cv_wait_interruptible() function was added
to handle this case. It behaves identically to cv_wait() with the
exception that it waits interruptibly allowing a signal to wake it
up. This means you do need to be careful and check issig() after
waking.
When dumping a debug log first check that it is safe to create
a new thread and block waiting for it. If we are in an atomic
context or irqs and disabled it is not safe to sleep and we
must write out of the debug log from the current process.
During module init spl_setup()->The vn_set_pwd("/") was failing
with -EFAULT because user_path_dir() and __user_walk() both
expect 'filename' to be a user space address and it's not in
this case. To handle this the data segment size is increased
to to ensure strncpy_from_user() does not fail with -EFAULT.
Additionally, I've added a printk() warning to catch this and
log it to the console if it ever reoccurs. I thought everything
was working properly here because there consequences of this
failing are subtle and usually non-critical.
We need dependent packages to be able to include spl_config.h to
build properly. This was partially solved in commit 0cbaeb1 by using
AH_BOTTOM to #undef common #defines (PACKAGE, VERSION, etc) which
autoconf always adds and cannot be easily removed. This solution
works as long as the spl_config.h is included before your projects
config.h. That turns out to be easier said than done. In particular,
this is a problem when your package includes its config.h using the
-include gcc option which ensures the first thing included is your
config.h.
To handle all cases cleanly I have removed the AH_BOTTOM hack and
replaced it with an AC_CONFIG_HEADERS command. This command runs
immediately after spl_config.h is written and with a little awk-foo
it strips the offending #defines from the file. This eliminates
the problem entirely and makes header safe for inclusion.
Also in this change I have removed the few places in the code where
spl_config.h is included. It is now added to the gcc compile line
to ensure the config results are always available.
Finally, I have also disabled the verbose kernel builds. If you
want them back you can always build with 'make V=1'. Since things
are working now they don't need to be on by default.
Allowing MAX_ORDER-1 sized allocations for kmem based slabs have
been observed to result in deadlocks. To help prvent this limit
max kmem based slab size to MAX_ORDER-3. Just for the record
callers should not be creating slabs like this, but if they do
we should still handle it as safely as we can.
As of linux-2.6.32 the 'struct file *filp' argument was dropped from
the proc_handle() prototype. It was apparently unused _almost_
everywhere in the kernel and this was simply cleanup.
I've added a new SPL_AC_5ARGS_PROC_HANDLER autoconf check for this and
the proper compat macros to correctly define the prototypes and some
helper functions. It's not pretty but API compat changes rarely are.
Fix panic() string, which was being used as a format string, instead of an already-formatted string.
Signed-off-by: Ricardo M. Correia <Ricardo.M.Correia@Sun.COM>
This test case verifies the correct behavior of taskq_wait_id().
In particular it ensure the the following two cases are handled
properly:
1) Task ids larger than the waited for task id can run and
complete as long as there is an available worker thread.
2) All task ids lower than the waited one must complete before
unblocking even if the waited task id itself has completed.
In the initial version of taskq_lowest_id() the entire pending and
work list was locked under the tq->tq_lock to determine the lowest
outstanding taskqid. At the time this done because I was rushed
and wanted to make sure it was right... fast was secondary. Well now
fast is important too so I carefully thought through the pending
and work list management and convinced myself it is safe and correct
to simply check the first entry. I added a large comment to the source
to explain this. But basically as long as we are careful to ensure the
pending and work list stay sorted this is safe and fast.
The motivation for this chance was that I was observing as much as
10% of the total CPU time go to waiting on the tq->tq_lock when the
pending list was long. This resolves that problems and frees up
that CPU time for something useful.
This regression test could crash in splat_kmem_cache_test_reclaim()
due to a race between the slab relclaim and the normal exiting of
the thread. Specifically, the kct structure could be free'd by
the thread performing the allocations while the reclaim function
was also working on that's threads kct structure. The simplest
fix is to extend the kcp->kcp_lock over the reclaim to prevent
the kct from being freed. A better fix would be to ref count
these structures, but since is just a regression this locking
change is enough. Surprisingly this was only observed commonly
under RHEL5.4 but all platform could have hit this.
I must have been in a hurry when I wrote the vnode regression tests
because the error code handling is not correct. The Solaris vnode
API returns positive errno's, these need to be converted to negative
errno's for Linux before being passed back to user space. Otherwise
the test hardness with report the failure but errno will not be set
with the correct error code.
Additionally tests 3, 4, 6, and 7 may fail in the test file already
exists. To avoid false positives a user mode helper has added to
remove the test files in /tmp/ before running the actual test.
This patch is another step towards updating the code to handle the
32-bit kernels which I have not been regularly testing. This changes
do not really impact the common case I'm expected which is the latest
kernel running on an x86_64 arch.
Until the linux-2.6.31 kernel the x86 arch did not have support for
64-bit atomic operations. Additionally, the new atomic_compat.h support
for this case was wrong because it embedded a spinlock in the atomic
variable which must always and only be 64-bits total. To handle these
32-bit issues we now simply fall back to the --enable-atomic-spinlock
implementation if the kernel does not provide the 64-bit atomic funcs.
The second issue this patch addresses is the DEBUG_KMEM assumption that
there will always be atomic64 funcs available. On 32-bit archs this may
not be true, and actually that's just fine. In that case the kernel will
will never be able to allocate more the 32-bits worth anyway. So just
check if atomic64 funcs are available, if they are not it means this
is a 32-bit machine and we can safely use atomic_t's instead.
The big fix here is the removal of kmalloc() in kv_alloc(). It used
to be true in previous kernels that kmallocs over PAGE_SIZE would
always be pages aligned. This is no longer true atleast in 2.6.31
there are no longer any alignment expectations. Since kv_alloc()
requires the resulting address to be page align we no only either
directly allocate pages in the KMC_KMEM case, or directly call
__vmalloc() both of which will always return a page aligned address.
Additionally, to avoid wasting memory size is always a power of two.
As for cleanup several helper functions were introduced to calculate
the aligned sizes of various data structures. This helps ensure no
case is accidentally missed where the alignment needs to be taken in
to account. The helpers now use P2ROUNDUP_TYPE instead of P2ROUNDUP
which is safer since the type will be explict and we no longer count
on the compiler to auto promote types hopefully as we expected.
Always wnforce minimum (SPL_KMEM_CACHE_ALIGN) and maximum (PAGE_SIZE)
alignment restrictions at cache creation time.
Use SPL_KMEM_CACHE_ALIGN in splat alignment test.
As of 2.6.31 it's clear __GFP_NOFAIL should no longer be used and it
may disappear from the kernel at any time. To handle this I have simply
added *_nofail wrappers in the kmem implementation which perform the
retry for non-atomic allocations.
From linux-2.6.31 mm/page_alloc.c:1166
/*
* __GFP_NOFAIL is not to be used in new code.
*
* All __GFP_NOFAIL callers should be fixed so that they
* properly detect and handle allocation failures.
*
* We most definitely don't want callers attempting to
* allocate greater than order-1 page units with
* __GFP_NOFAIL.
*/
WARN_ON_ONCE(order > 1);
