From 89ac5a1d2a32e9cc520ed5a8a2ff217e11a962eb Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 7 Oct 2019 15:36:39 +0100 Subject: [PATCH] migration: Use automatic rcu_read unlock in ram.c MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Use the automatic read unlocker in migration/ram.c Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Daniel P. Berrangé Message-Id: <20191007143642.301445-4-dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- migration/ram.c | 259 ++++++++++++++++++++++++++------------------------------ 1 file changed, 121 insertions(+), 138 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 484d66379a..e29c8b3408 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -181,14 +181,14 @@ int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque) RAMBlock *block; int ret = 0; - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); + RAMBLOCK_FOREACH_NOT_IGNORED(block) { ret = func(block, opaque); if (ret) { break; } } - rcu_read_unlock(); return ret; } @@ -1848,12 +1848,12 @@ static void migration_bitmap_sync(RAMState *rs) memory_global_dirty_log_sync(); qemu_mutex_lock(&rs->bitmap_mutex); - rcu_read_lock(); - RAMBLOCK_FOREACH_NOT_IGNORED(block) { - ramblock_sync_dirty_bitmap(rs, block); + WITH_RCU_READ_LOCK_GUARD() { + RAMBLOCK_FOREACH_NOT_IGNORED(block) { + ramblock_sync_dirty_bitmap(rs, block); + } + ram_counters.remaining = ram_bytes_remaining(); } - ram_counters.remaining = ram_bytes_remaining(); - rcu_read_unlock(); qemu_mutex_unlock(&rs->bitmap_mutex); memory_global_after_dirty_log_sync(); @@ -2397,13 +2397,12 @@ static void migration_page_queue_free(RAMState *rs) /* This queue generally should be empty - but in the case of a failed * migration might have some droppings in. */ - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); QSIMPLEQ_FOREACH_SAFE(mspr, &rs->src_page_requests, next_req, next_mspr) { memory_region_unref(mspr->rb->mr); QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req); g_free(mspr); } - rcu_read_unlock(); } /** @@ -2424,7 +2423,8 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len) RAMState *rs = ram_state; ram_counters.postcopy_requests++; - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); + if (!rbname) { /* Reuse last RAMBlock */ ramblock = rs->last_req_rb; @@ -2466,12 +2466,10 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len) QSIMPLEQ_INSERT_TAIL(&rs->src_page_requests, new_entry, next_req); migration_make_urgent_request(); qemu_mutex_unlock(&rs->src_page_req_mutex); - rcu_read_unlock(); return 0; err: - rcu_read_unlock(); return -1; } @@ -2700,7 +2698,8 @@ static uint64_t ram_bytes_total_common(bool count_ignored) RAMBlock *block; uint64_t total = 0; - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); + if (count_ignored) { RAMBLOCK_FOREACH_MIGRATABLE(block) { total += block->used_length; @@ -2710,7 +2709,6 @@ static uint64_t ram_bytes_total_common(bool count_ignored) total += block->used_length; } } - rcu_read_unlock(); return total; } @@ -3034,7 +3032,7 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms) RAMBlock *block; int ret; - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); /* This should be our last sync, the src is now paused */ migration_bitmap_sync(rs); @@ -3048,7 +3046,6 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms) /* Deal with TPS != HPS and huge pages */ ret = postcopy_chunk_hostpages(ms, block); if (ret) { - rcu_read_unlock(); return ret; } @@ -3060,7 +3057,6 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms) trace_ram_postcopy_send_discard_bitmap(); ret = postcopy_each_ram_send_discard(ms); - rcu_read_unlock(); return ret; } @@ -3081,7 +3077,7 @@ int ram_discard_range(const char *rbname, uint64_t start, size_t length) trace_ram_discard_range(rbname, start, length); - rcu_read_lock(); + RCU_READ_LOCK_GUARD(); RAMBlock *rb = qemu_ram_block_by_name(rbname); if (!rb) { @@ -3101,8 +3097,6 @@ int ram_discard_range(const char *rbname, uint64_t start, size_t length) ret = ram_block_discard_range(rb, start, length); err: - rcu_read_unlock(); - return ret; } @@ -3231,13 +3225,12 @@ static void ram_init_bitmaps(RAMState *rs) /* For memory_global_dirty_log_start below. */ qemu_mutex_lock_iothread(); qemu_mutex_lock_ramlist(); - rcu_read_lock(); - ram_list_init_bitmaps(); - memory_global_dirty_log_start(); - migration_bitmap_sync_precopy(rs); - - rcu_read_unlock(); + WITH_RCU_READ_LOCK_GUARD() { + ram_list_init_bitmaps(); + memory_global_dirty_log_start(); + migration_bitmap_sync_precopy(rs); + } qemu_mutex_unlock_ramlist(); qemu_mutex_unlock_iothread(); } @@ -3424,55 +3417,57 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) goto out; } - rcu_read_lock(); - if (ram_list.version != rs->last_version) { - ram_state_reset(rs); - } - - /* Read version before ram_list.blocks */ - smp_rmb(); + WITH_RCU_READ_LOCK_GUARD() { + if (ram_list.version != rs->last_version) { + ram_state_reset(rs); + } - ram_control_before_iterate(f, RAM_CONTROL_ROUND); + /* Read version before ram_list.blocks */ + smp_rmb(); - t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); - i = 0; - while ((ret = qemu_file_rate_limit(f)) == 0 || - !QSIMPLEQ_EMPTY(&rs->src_page_requests)) { - int pages; + ram_control_before_iterate(f, RAM_CONTROL_ROUND); - if (qemu_file_get_error(f)) { - break; - } + t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + i = 0; + while ((ret = qemu_file_rate_limit(f)) == 0 || + !QSIMPLEQ_EMPTY(&rs->src_page_requests)) { + int pages; - pages = ram_find_and_save_block(rs, false); - /* no more pages to sent */ - if (pages == 0) { - done = 1; - break; - } + if (qemu_file_get_error(f)) { + break; + } - if (pages < 0) { - qemu_file_set_error(f, pages); - break; - } + pages = ram_find_and_save_block(rs, false); + /* no more pages to sent */ + if (pages == 0) { + done = 1; + break; + } - rs->target_page_count += pages; - - /* we want to check in the 1st loop, just in case it was the 1st time - and we had to sync the dirty bitmap. - qemu_clock_get_ns() is a bit expensive, so we only check each some - iterations - */ - if ((i & 63) == 0) { - uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) / 1000000; - if (t1 > MAX_WAIT) { - trace_ram_save_iterate_big_wait(t1, i); + if (pages < 0) { + qemu_file_set_error(f, pages); break; } + + rs->target_page_count += pages; + + /* + * we want to check in the 1st loop, just in case it was the 1st + * time and we had to sync the dirty bitmap. + * qemu_clock_get_ns() is a bit expensive, so we only check each + * some iterations + */ + if ((i & 63) == 0) { + uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) / + 1000000; + if (t1 > MAX_WAIT) { + trace_ram_save_iterate_big_wait(t1, i); + break; + } + } + i++; } - i++; } - rcu_read_unlock(); /* * Must occur before EOS (or any QEMUFile operation) @@ -3510,35 +3505,33 @@ static int ram_save_complete(QEMUFile *f, void *opaque) RAMState *rs = *temp; int ret = 0; - rcu_read_lock(); - - if (!migration_in_postcopy()) { - migration_bitmap_sync_precopy(rs); - } + WITH_RCU_READ_LOCK_GUARD() { + if (!migration_in_postcopy()) { + migration_bitmap_sync_precopy(rs); + } - ram_control_before_iterate(f, RAM_CONTROL_FINISH); + ram_control_before_iterate(f, RAM_CONTROL_FINISH); - /* try transferring iterative blocks of memory */ + /* try transferring iterative blocks of memory */ - /* flush all remaining blocks regardless of rate limiting */ - while (true) { - int pages; + /* flush all remaining blocks regardless of rate limiting */ + while (true) { + int pages; - pages = ram_find_and_save_block(rs, !migration_in_colo_state()); - /* no more blocks to sent */ - if (pages == 0) { - break; - } - if (pages < 0) { - ret = pages; - break; + pages = ram_find_and_save_block(rs, !migration_in_colo_state()); + /* no more blocks to sent */ + if (pages == 0) { + break; + } + if (pages < 0) { + ret = pages; + break; + } } - } - - flush_compressed_data(rs); - ram_control_after_iterate(f, RAM_CONTROL_FINISH); - rcu_read_unlock(); + flush_compressed_data(rs); + ram_control_after_iterate(f, RAM_CONTROL_FINISH); + } multifd_send_sync_main(rs); qemu_put_be64(f, RAM_SAVE_FLAG_EOS); @@ -3561,9 +3554,9 @@ static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size, if (!migration_in_postcopy() && remaining_size < max_size) { qemu_mutex_lock_iothread(); - rcu_read_lock(); - migration_bitmap_sync_precopy(rs); - rcu_read_unlock(); + WITH_RCU_READ_LOCK_GUARD() { + migration_bitmap_sync_precopy(rs); + } qemu_mutex_unlock_iothread(); remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE; } @@ -3907,7 +3900,13 @@ int colo_init_ram_cache(void) error_report("%s: Can't alloc memory for COLO cache of block %s," "size 0x" RAM_ADDR_FMT, __func__, block->idstr, block->used_length); - goto out_locked; + RAMBLOCK_FOREACH_NOT_IGNORED(block) { + if (block->colo_cache) { + qemu_anon_ram_free(block->colo_cache, block->used_length); + block->colo_cache = NULL; + } + } + return -errno; } memcpy(block->colo_cache, block->host, block->used_length); } @@ -3933,18 +3932,6 @@ int colo_init_ram_cache(void) memory_global_dirty_log_start(); return 0; - -out_locked: - - RAMBLOCK_FOREACH_NOT_IGNORED(block) { - if (block->colo_cache) { - qemu_anon_ram_free(block->colo_cache, block->used_length); - block->colo_cache = NULL; - } - } - - rcu_read_unlock(); - return -errno; } /* It is need to hold the global lock to call this helper */ @@ -3958,16 +3945,14 @@ void colo_release_ram_cache(void) block->bmap = NULL; } - rcu_read_lock(); - - RAMBLOCK_FOREACH_NOT_IGNORED(block) { - if (block->colo_cache) { - qemu_anon_ram_free(block->colo_cache, block->used_length); - block->colo_cache = NULL; + WITH_RCU_READ_LOCK_GUARD() { + RAMBLOCK_FOREACH_NOT_IGNORED(block) { + if (block->colo_cache) { + qemu_anon_ram_free(block->colo_cache, block->used_length); + block->colo_cache = NULL; + } } } - - rcu_read_unlock(); qemu_mutex_destroy(&ram_state->bitmap_mutex); g_free(ram_state); ram_state = NULL; @@ -4205,31 +4190,30 @@ static void colo_flush_ram_cache(void) unsigned long offset = 0; memory_global_dirty_log_sync(); - rcu_read_lock(); - RAMBLOCK_FOREACH_NOT_IGNORED(block) { - ramblock_sync_dirty_bitmap(ram_state, block); + WITH_RCU_READ_LOCK_GUARD() { + RAMBLOCK_FOREACH_NOT_IGNORED(block) { + ramblock_sync_dirty_bitmap(ram_state, block); + } } - rcu_read_unlock(); trace_colo_flush_ram_cache_begin(ram_state->migration_dirty_pages); - rcu_read_lock(); - block = QLIST_FIRST_RCU(&ram_list.blocks); + WITH_RCU_READ_LOCK_GUARD() { + block = QLIST_FIRST_RCU(&ram_list.blocks); - while (block) { - offset = migration_bitmap_find_dirty(ram_state, block, offset); + while (block) { + offset = migration_bitmap_find_dirty(ram_state, block, offset); - if (offset << TARGET_PAGE_BITS >= block->used_length) { - offset = 0; - block = QLIST_NEXT_RCU(block, next); - } else { - migration_bitmap_clear_dirty(ram_state, block, offset); - dst_host = block->host + (offset << TARGET_PAGE_BITS); - src_host = block->colo_cache + (offset << TARGET_PAGE_BITS); - memcpy(dst_host, src_host, TARGET_PAGE_SIZE); + if (offset << TARGET_PAGE_BITS >= block->used_length) { + offset = 0; + block = QLIST_NEXT_RCU(block, next); + } else { + migration_bitmap_clear_dirty(ram_state, block, offset); + dst_host = block->host + (offset << TARGET_PAGE_BITS); + src_host = block->colo_cache + (offset << TARGET_PAGE_BITS); + memcpy(dst_host, src_host, TARGET_PAGE_SIZE); + } } } - - rcu_read_unlock(); trace_colo_flush_ram_cache_end(); } @@ -4428,16 +4412,15 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) * it will be necessary to reduce the granularity of this * critical section. */ - rcu_read_lock(); + WITH_RCU_READ_LOCK_GUARD() { + if (postcopy_running) { + ret = ram_load_postcopy(f); + } else { + ret = ram_load_precopy(f); + } - if (postcopy_running) { - ret = ram_load_postcopy(f); - } else { - ret = ram_load_precopy(f); + ret |= wait_for_decompress_done(); } - - ret |= wait_for_decompress_done(); - rcu_read_unlock(); trace_ram_load_complete(ret, seq_iter); if (!ret && migration_incoming_in_colo_state()) { -- 2.11.0