xen: Add -Wno-unused-value to the clang CFLAGS

clang complains about a lot of functions and macros whose return value
is unused.  I started on patches to drop some functions' return values
and scatter (void)s around callers, but it was getting too messy.
Just turn off the warning instead.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
x86/mm: Another couple of comparisons of unsigned vars with < 0.

Adding the explicit (unsigned) casts in case enums ever end up signed.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
x86: fix logical ANDs used to mask bitfields.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
x86: fix memset(ptr, 0, sizeof ptr).

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Christoph Egger <Christoph.Egger@amd.com>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
x86: don't use .subsection when compiling with clang

LLVM's assembler doesn't support the .subsection directive, so put
the out-of-line failure path in .fixup instead.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
xen: define __section() and friends and use them for section annotations.

By itself this is just code-tidying, but it's also useful for the
following patch, which will adjust __section() for clang compiles.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
x86: explicitly mark __initdata variables as used when building with clang.

This stops LLVM from replacing it with a different, auto-generated
variable as part of an optimization.  (The auto-generated variable
ends up in the normal data section.)

Remove stray __read_mostly annotations on declarations that this unmasked.

Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Keir Fraser <keir@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
.gitignore: Add a missing file

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: ao: allow immediate completion

Make it possible to complete an ao during its initating function.

Previously this was not generally possible because initiators did not
have an egc.  But there is no reason why an ao initiator should not
have an egc, so make the standard macros provide one.

Change the internal documentation comments accordingly.  (This change,
which means that an initiator function may call a completion callback
directly, is already consistent with the documented external API.)

We also invent of a new state flag "constructing" which indicates
whether we are between ao__create and ao__inprogress.  This is a
slightly optimisation which allows ao_complete to not bother poking
the wakeup pipe, since the logic in ao__inprogress will not run the
event loop if the ao is complete on entry.

Also fix the wording in the libxl_internal.h comment forbidding use of
ao_how-taking functions from within libxl.  (There are sadly currently
some such functions.)

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: fix hang due to libxl__initiate_device_remove

libxl__initiate_device_remove might discover that the operation was
complete, immediately (typically, if the device is already removed).

Previously, in this situation, it would return 0 to the caller but
never call libxl__ao_complete.  Fix this.  This necessitates passing
the egc in from the functions which are the ao initiators.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Fix eventloop_iteration over-locking

eventloop_iteration's head comment says that it must be called with
the ctx locked exactly once, and this is indeed true, and it's done
correctly at both the call sites.

However, it takes out the lock an additional time itself.  This is
wrong because it prevents the unlocks around poll from being
effective.  This would mean that a multithreaded event-loop using
program might suffer from undesired blocking, as one thread trying to
enter libxl might end up stalled by another thread waiting for a slow
event.  So remove those two lock calls.

Also add a couple of comments documenting the locking behaviour of
libxl__ao_inprogress and libxl__egc_cleanup.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: remove poller from list in libxl__poller_get

Remove poller from the list once it has been requested.
Fixes a double-free bug.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Fix leak of ctx->lock

A mutex created with pthread_mutex_init, like ctx->lock, may need to
be destroyed with pthread_mutex_destroy.

Also, previously, if libxl__init_recursive_mutex failed, the nascent
ctx would be leaked.  Add some comments which will hopefully make
these kind of mistakes less likely in future.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
tools: Correct PTHREAD options in config/StdGNU.mk

It is not correct to say -lpthread.  The correct option is -pthread,
which may have sundry other effects on code generation etc.  It needs
to be passed both to compilation and linking.

Fix the configure test to test -pthread, and plumb the resulting flag
through to PTHREAD_{CFLAGS,LDFLAGS} in Tools.mk; also substitute
PTHREAD_LIBS (although this will currently always be empty).
Remove PTHREAD_LIBS setting from StdGNU.mk.

Fix the one user (libxc) to use PTHREAD_{CFLAGS,LDFLAGS} too.

There are still some other users in tree which pass -pthread or
-lpthread by adding it as a literal to their own compiler options.
These will be fixed in a later patch.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Use PTHREAD_CFLAGS, LDFLAGS, LIBS

This is going to be needed for pthread_atfork.  It is a mystery why it
hasn't been needed before.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
tools: Use PTHREAD_CFLAGS, _LDFLAGS, _LIBS

Replace all literal occurrences of -lpthread and -pthread in Makefiles
by references to PTHREAD_CFLAGS, PTHREAD_LDFLAGS and PTHREAD_LIBS.
These are the new variables set by configure, and currently expand to
-pthread on the compilation and link lines as is required.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Crash (more sensibly) on malloc failure

Formally change the libxl memory allocation failure policy to "crash".

Previously we had a very uneven approach; much code assumed that
libxl__sprintf (for example) would never return NULL, but some code
was written more carefully.

We think it is unlikely that we will be able to make the library
actually robust against allocation failure (since that would be an
awful lot of never-tested error paths) and few calling environments
will be able to cope anyway.  So, instead, adopt the alternative
approach: provide allocation functions which never return null, but
will crash the whole process instead.

Consequently,
 - New noreturn function libxl__alloc_failed which may be used for
   printing a vaguely-useful error message, rather than simply
   dereferencing a null pointer.
 - libxl__ptr_add now returns void as it crashes on failure.
 - libxl__zalloc, _calloc, _strdup, _strndup, crash on failure using
   libxl__alloc_failed.  So all the code that uses these can no longer
   dereference null on malloc failure.

While we're at it, make libxl__ptr_add use realloc rather than
emulating it with calloc and free, and make it grow the array
exponentially rather than linearly.

Things left to do:
 - Remove a lot of now-spurious error handling.
 - Remove the ERROR_NOMEM error code.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Make libxl__zalloc et al tolerate a NULL gc

Arrange that if we pass NULL as a gc, we simply don't register the
pointer.  This instantly gives us non-gc'ing but error-checking
versions of malloc, realloc, vasprintf, etc.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: Introduce some convenience macros

We introduce:
   <type> *GCNEW(<type> *var);
   <type> *GCNEW_ARRAY(<type> *var, ssize_t nmemb);
   <type> *GCREALLOC_ARRAY(<type> *var, size_t nmemb);
   char *GCSPRINTF(const char *fmt, ...);
   void LOG(<xtl_level_suffix>, const char *fmt, ...);
   void LOGE(<xtl_level_suffix>, const char *fmt, ...);
   void LOGEV(<xtl_level_suffix>, int errnoval, const char *fmt, ...);
all of which expect, in the calling context,
   libxl__gc *gc;

Most of these will find callers in subsequent patches.  The exceptions
are the orthogonally necessary LOGE and LOGEV, and GCREALLOC_ARRAY.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: include <ctype.h> and introduce CTYPE helper macro

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>