[2/3] migration: Use automatic rcu_read unlock in ram.c
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Message ID 20190911164202.31136-3-dgilbert@redhat.com
State New
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Series
  • Automatic RCU read unlock
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Commit Message

Dr. David Alan Gilbert Sept. 11, 2019, 4:42 p.m. UTC
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Use the automatic read unlocker in migration/ram.c;
only for the cases where the unlock is at the end of the function.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/ram.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

Comments

Daniel P. Berrangé Sept. 11, 2019, 4:59 p.m. UTC | #1
On Wed, Sep 11, 2019 at 05:42:01PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Use the automatic read unlocker in migration/ram.c;
> only for the cases where the unlock is at the end of the function.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/ram.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index b2bd618a89..750d198f37 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_AUTO

FWIW, I'm not a fan of macros which are used without a trailing ';'
as I believe it can confuses editors' code indentation logic.


Regards,
Daniel
Dr. David Alan Gilbert Sept. 11, 2019, 5:25 p.m. UTC | #2
* Daniel P. Berrangé (berrange@redhat.com) wrote:
> On Wed, Sep 11, 2019 at 05:42:01PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Use the automatic read unlocker in migration/ram.c;
> > only for the cases where the unlock is at the end of the function.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  migration/ram.c | 25 +++++++++----------------
> >  1 file changed, 9 insertions(+), 16 deletions(-)
> > 
> > diff --git a/migration/ram.c b/migration/ram.c
> > index b2bd618a89..750d198f37 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_AUTO
> 
> FWIW, I'm not a fan of macros which are used without a trailing ';'
> as I believe it can confuses editors' code indentation logic.

Added.

> 
> Regards,
> Daniel
> -- 
> |: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
> |: https://libvirt.org         -o-            https://fstop138.berrange.com :|
> |: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Patch
diff mbox series

diff --git a/migration/ram.c b/migration/ram.c
index b2bd618a89..750d198f37 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_AUTO
+
     RAMBLOCK_FOREACH_NOT_IGNORED(block) {
         ret = func(block, opaque);
         if (ret) {
             break;
         }
     }
-    rcu_read_unlock();
     return ret;
 }
 
@@ -2398,13 +2398,12 @@  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_AUTO
     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();
 }
 
 /**
@@ -2425,7 +2424,8 @@  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_AUTO
+
     if (!rbname) {
         /* Reuse last RAMBlock */
         ramblock = rs->last_req_rb;
@@ -2467,12 +2467,10 @@  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;
 }
 
@@ -2712,7 +2710,8 @@  static uint64_t ram_bytes_total_common(bool count_ignored)
     RAMBlock *block;
     uint64_t total = 0;
 
-    rcu_read_lock();
+    RCU_READ_LOCK_AUTO
+
     if (count_ignored) {
         RAMBLOCK_FOREACH_MIGRATABLE(block) {
             total += block->used_length;
@@ -2722,7 +2721,6 @@  static uint64_t ram_bytes_total_common(bool count_ignored)
             total += block->used_length;
         }
     }
-    rcu_read_unlock();
     return total;
 }
 
@@ -3086,7 +3084,7 @@  int ram_postcopy_send_discard_bitmap(MigrationState *ms)
     RAMBlock *block;
     int ret;
 
-    rcu_read_lock();
+    RCU_READ_LOCK_AUTO
 
     /* This should be our last sync, the src is now paused */
     migration_bitmap_sync(rs);
@@ -3107,13 +3105,11 @@  int ram_postcopy_send_discard_bitmap(MigrationState *ms)
              * point.
              */
             error_report("migration ram resized during precopy phase");
-            rcu_read_unlock();
             return -EINVAL;
         }
         /* Deal with TPS != HPS and huge pages */
         ret = postcopy_chunk_hostpages(ms, block);
         if (ret) {
-            rcu_read_unlock();
             return ret;
         }
 
@@ -3128,7 +3124,6 @@  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;
 }
@@ -3149,7 +3144,7 @@  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_AUTO
     RAMBlock *rb = qemu_ram_block_by_name(rbname);
 
     if (!rb) {
@@ -3169,8 +3164,6 @@  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;
 }