> Subject: [PATCH v2 2/2] Init the XBZRLE.lock in ram_mig_init > > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > Initialising the XBZRLE.lock earlier simplifies the lock use. > > Based on Markus's patch in: > http://lists.gnu.org/archive/html/qemu-devel/2014-03/msg03879.html > > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com> > --- > arch_init.c | 61 > +++++++++++++++++++++++++++++++------------------------------ > 1 file changed, 31 insertions(+), 30 deletions(-) > > diff --git a/arch_init.c b/arch_init.c > index 0d2bf84..f18f42e 100644 > --- a/arch_init.c > +++ b/arch_init.c > @@ -45,6 +45,7 @@ > #include "hw/audio/pcspk.h" > #include "migration/page_cache.h" > #include "qemu/config-file.h" > +#include "qemu/error-report.h" > #include "qmp-commands.h" > #include "trace.h" > #include "exec/cpu-all.h" > @@ -167,11 +168,8 @@ static struct { > /* Cache for XBZRLE, Protected by lock. */ > PageCache *cache; > QemuMutex lock; > -} XBZRLE = { > - .encoded_buf = NULL, > - .current_buf = NULL, > - .cache = NULL, > -}; > +} XBZRLE; > + > /* buffer used for XBZRLE decoding */ > static uint8_t *xbzrle_decoded_buf; > > @@ -187,41 +185,44 @@ static void XBZRLE_cache_unlock(void) > qemu_mutex_unlock(&XBZRLE.lock); > } > > +/* > + * called from qmp_migrate_set_cache_size in main thread, possibly while > + * a migration is in progress. > + * A running migration maybe using the cache and might finish during this > + * call, hence changes to the cache are protected by XBZRLE.lock(). > + */ > int64_t xbzrle_cache_resize(int64_t new_size) > { > - PageCache *new_cache, *cache_to_free; > + PageCache *new_cache; > + int64_t ret; > > if (new_size < TARGET_PAGE_SIZE) { > return -1; > } > > - /* no need to lock, the current thread holds qemu big lock */ > + XBZRLE_cache_lock(); > + > if (XBZRLE.cache != NULL) { > - /* check XBZRLE.cache again later */ > if (pow2floor(new_size) == migrate_xbzrle_cache_size()) { > - return pow2floor(new_size); > + goto out_new_size; > } > new_cache = cache_init(new_size / TARGET_PAGE_SIZE, > TARGET_PAGE_SIZE); > if (!new_cache) { > - DPRINTF("Error creating cache\n"); > - return -1; > - } > - > - XBZRLE_cache_lock(); > - /* the XBZRLE.cache may have be destroyed, check it again */ > - if (XBZRLE.cache != NULL) { > - cache_to_free = XBZRLE.cache; > - XBZRLE.cache = new_cache; > - } else { > - cache_to_free = new_cache; > + error_report("Error creating cache"); > + ret = -1; > + goto out; > } > - XBZRLE_cache_unlock(); > > - cache_fini(cache_to_free); > + cache_fini(XBZRLE.cache); > + XBZRLE.cache = new_cache; > } > > - return pow2floor(new_size); > +out_new_size: > + ret = pow2floor(new_size); > +out: > + XBZRLE_cache_unlock(); > + return ret; > } > > /* accounting for migration statistics */ > @@ -735,28 +736,27 @@ static int ram_save_setup(QEMUFile *f, void > *opaque) > dirty_rate_high_cnt = 0; > > if (migrate_use_xbzrle()) { > - qemu_mutex_lock_iothread(); > + XBZRLE_cache_lock(); > XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() / > TARGET_PAGE_SIZE, > TARGET_PAGE_SIZE); > if (!XBZRLE.cache) { > - qemu_mutex_unlock_iothread(); > - DPRINTF("Error creating cache\n"); > + XBZRLE_cache_unlock(); > + error_report("Error creating cache"); > return -1; > } > - qemu_mutex_init(&XBZRLE.lock); > - qemu_mutex_unlock_iothread(); > + XBZRLE_cache_unlock(); > > /* We prefer not to abort if there is no memory */ > XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE); > if (!XBZRLE.encoded_buf) { > - DPRINTF("Error allocating encoded_buf\n"); > + error_report("Error allocating encoded_buf"); > return -1; > } > > XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE); > if (!XBZRLE.current_buf) { > - DPRINTF("Error allocating current_buf\n"); > + error_report("Error allocating current_buf"); > g_free(XBZRLE.encoded_buf); > XBZRLE.encoded_buf = NULL; > return -1; > @@ -1106,6 +1106,7 @@ static SaveVMHandlers savevm_ram_handlers = { > > void ram_mig_init(void) > { > + qemu_mutex_init(&XBZRLE.lock); > register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, > NULL); > } > > -- > 1.8.5.3
Reviewed-by: Gonglei <arei.gong...@huawei.com> Best regards, -Gonglei
