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From: Juan Quintela <quintela@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Juan Quintela <quintela@redhat.com>,
	Laurent Vivier <lvivier@redhat.com>,
	kvm@vger.kernel.org, Thomas Huth <thuth@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>
Subject: [PULL 09/19] migration: No need to take rcu during sync_dirty_bitmap
Date: Thu, 11 Jul 2019 12:44:02 +0200
Message-ID: <20190711104412.31233-10-quintela@redhat.com> (raw)
In-Reply-To: <20190711104412.31233-1-quintela@redhat.com>

From: Peter Xu <peterx@redhat.com>

cpu_physical_memory_sync_dirty_bitmap() has one RAMBlock* as
parameter, which means that it must be with RCU read lock held
already.  Taking it again inside seems redundant.  Removing it.
Instead comment on the functions about the RCU read lock.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190603065056.25211-2-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 include/exec/ram_addr.h | 5 +----
 migration/ram.c         | 1 +
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index f96777bb99..44dcc98de6 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -409,6 +409,7 @@ static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start,
 }
 
 
+/* Called with RCU critical section */
 static inline
 uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                                                ram_addr_t start,
@@ -432,8 +433,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                                         DIRTY_MEMORY_BLOCK_SIZE);
         unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
 
-        rcu_read_lock();
-
         src = atomic_rcu_read(
                 &ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION])->blocks;
 
@@ -453,8 +452,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                 idx++;
             }
         }
-
-        rcu_read_unlock();
     } else {
         ram_addr_t offset = rb->offset;
 
diff --git a/migration/ram.c b/migration/ram.c
index 89eec7ee9d..48969db84b 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1674,6 +1674,7 @@ static inline bool migration_bitmap_clear_dirty(RAMState *rs,
     return ret;
 }
 
+/* Called with RCU critical section */
 static void migration_bitmap_sync_range(RAMState *rs, RAMBlock *rb,
                                         ram_addr_t length)
 {
-- 
2.21.0


  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 10:43 [PULL 00/19] Migration patches Juan Quintela
2019-07-11 10:43 ` [PULL 01/19] migration: fix multifd_recv event typo Juan Quintela
2019-07-11 10:43 ` [PULL 02/19] migration-test: rename parameter to parameter_int Juan Quintela
2019-07-11 10:43 ` [PULL 03/19] migration-test: Add migration multifd test Juan Quintela
2019-07-11 10:43 ` [PULL 04/19] migration/multifd: call multifd_send_sync_main when sending RAM_SAVE_FLAG_EOS Juan Quintela
2019-07-11 10:43 ` [PULL 05/19] migration/xbzrle: update cache and current_data in one place Juan Quintela
2019-07-11 10:43 ` [PULL 06/19] cutils: remove one unnecessary pointer operation Juan Quintela
2019-07-11 10:44 ` [PULL 07/19] migration/multifd: sync packet_num after all thread are done Juan Quintela
2019-07-11 10:44 ` [PULL 08/19] migratioin/ram.c: reset complete_round when we gets a queued page Juan Quintela
2019-07-11 10:44 ` Juan Quintela [this message]
2019-07-11 10:44 ` [PULL 10/19] memory: Don't set migration bitmap when without migration Juan Quintela
2019-07-11 10:44 ` [PULL 11/19] bitmap: Add bitmap_copy_with_{src|dst}_offset() Juan Quintela
2019-07-11 10:44 ` [PULL 12/19] memory: Pass mr into snapshot_and_clear_dirty Juan Quintela
2019-07-11 10:44 ` [PULL 13/19] memory: Introduce memory listener hook log_clear() Juan Quintela
2019-07-11 10:44 ` [PULL 14/19] kvm: Update comments for sync_dirty_bitmap Juan Quintela
2019-07-11 10:44 ` [PULL 15/19] kvm: Persistent per kvmslot dirty bitmap Juan Quintela
2019-07-11 10:44 ` [PULL 16/19] kvm: Introduce slots lock for memory listener Juan Quintela
2019-07-11 10:44 ` [PULL 17/19] kvm: Support KVM_CLEAR_DIRTY_LOG Juan Quintela
2019-07-11 10:44 ` [PULL 19/19] migration: allow private destination ram with x-ignore-shared Juan Quintela
2019-07-11 11:19 ` [PULL 00/19] Migration patches Paolo Bonzini
2019-07-11 11:32   ` Juan Quintela
2019-07-11 11:34   ` Dr. David Alan Gilbert
2019-07-11 11:40     ` [Qemu-devel] " Peter Maydell
2019-07-11 12:39 ` Peter Maydell
2019-07-12 14:06   ` Juan Quintela
2019-07-11 12:55 ` Christian Borntraeger
2019-07-11 13:01   ` [Qemu-devel] " Peter Maydell
2019-07-11 13:00 ` no-reply
2019-07-12 14:33 ` no-reply
2019-07-12 14:31 Juan Quintela
2019-07-12 14:31 ` [PULL 09/19] migration: No need to take rcu during sync_dirty_bitmap Juan Quintela

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