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Fri, 13 Dec 2019 15:03:43 +0000 (UTC) Date: Fri, 13 Dec 2019 15:03:41 +0000 From: "Dr. David Alan Gilbert" To: Paolo Bonzini , quintela@redhat.com, chen.zhang@intel.com Subject: Re: [PATCH] colo: fix return without releasing RCU Message-ID: <20191213150341.GG3713@work-vm> References: <1576246112-23406-2-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 In-Reply-To: <1576246112-23406-2-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: nn90rs3NMku3cY7Zu5vxGw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Paolo Bonzini (pbonzini@redhat.com) wrote: > Use WITH_RCU_READ_LOCK_GUARD to avoid exiting colo_init_ram_cache > without releasing RCU. >=20 > Cc: Dr. David Alan Gilbert > Signed-off-by: Paolo Bonzini Reviewed-by: Dr. David Alan Gilbert > --- > migration/ram.c | 33 +++++++++++++++++---------------- > 1 file changed, 17 insertions(+), 16 deletions(-) >=20 > diff --git a/migration/ram.c b/migration/ram.c > index 7dd7f81..8d7c015 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -3891,26 +3891,27 @@ int colo_init_ram_cache(void) > { > RAMBlock *block; > =20 > - rcu_read_lock(); > - RAMBLOCK_FOREACH_NOT_IGNORED(block) { > - block->colo_cache =3D qemu_anon_ram_alloc(block->used_length, > - NULL, > - false); > - if (!block->colo_cache) { > - error_report("%s: Can't alloc memory for COLO cache of block= %s," > - "size 0x" RAM_ADDR_FMT, __func__, block->idstr, > - block->used_length); > - RAMBLOCK_FOREACH_NOT_IGNORED(block) { > - if (block->colo_cache) { > - qemu_anon_ram_free(block->colo_cache, block->used_le= ngth); > - block->colo_cache =3D NULL; > + WITH_RCU_READ_LOCK_GUARD() { > + RAMBLOCK_FOREACH_NOT_IGNORED(block) { > + block->colo_cache =3D qemu_anon_ram_alloc(block->used_length= , > + NULL, > + false); > + if (!block->colo_cache) { > + error_report("%s: Can't alloc memory for COLO cache of b= lock %s," > + "size 0x" RAM_ADDR_FMT, __func__, block->id= str, > + block->used_length); > + RAMBLOCK_FOREACH_NOT_IGNORED(block) { > + if (block->colo_cache) { > + qemu_anon_ram_free(block->colo_cache, block->use= d_length); > + block->colo_cache =3D NULL; > + } > } > + return -errno; > } > - return -errno; > + memcpy(block->colo_cache, block->host, block->used_length); > } > - memcpy(block->colo_cache, block->host, block->used_length); > } > - rcu_read_unlock(); > + > /* > * Record the dirty pages that sent by PVM, we use this dirty bitmap = together > * with to decide which page in cache should be flushed into SVM's RA= M. Here > --=20 > 1.8.3.1 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK