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author | Olaf Hering <olaf@aepfle.de> | 2011-06-10 10:47:02 +0200 |
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committer | Olaf Hering <olaf@aepfle.de> | 2011-06-10 10:47:02 +0200 |
commit | 7910d6f2a5ac513fc01acc88aa7374a06ee0144b (patch) | |
tree | 2034a7a4e4e006fbe09341fb294ea56009004b02 /tools/xenpaging | |
parent | f37f72f2ccafe0566778b3e238c313d5fed364e4 (diff) | |
download | xen-7910d6f2a5ac513fc01acc88aa7374a06ee0144b.tar.gz xen-7910d6f2a5ac513fc01acc88aa7374a06ee0144b.tar.bz2 xen-7910d6f2a5ac513fc01acc88aa7374a06ee0144b.zip |
xenpaging: remove unused spinlock in pager
The spinlock code in the pager is a no-op because xenpaging is a single
threaded application. There is no locking when put_response() places a
response into the ringbuffer.
The only locking is inside the hypervisor, where mem_event_put_request() and
mem_event_get_response() lock the ringbuffer to protect multiple vcpus from
each other.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Diffstat (limited to 'tools/xenpaging')
-rw-r--r-- | tools/xenpaging/mem_event.h | 5 | ||||
-rw-r--r-- | tools/xenpaging/spinlock.h | 69 | ||||
-rw-r--r-- | tools/xenpaging/xenpaging.c | 12 | ||||
-rw-r--r-- | tools/xenpaging/xenpaging.h | 1 |
4 files changed, 0 insertions, 87 deletions
diff --git a/tools/xenpaging/mem_event.h b/tools/xenpaging/mem_event.h index 807b21816b..d6e403a7da 100644 --- a/tools/xenpaging/mem_event.h +++ b/tools/xenpaging/mem_event.h @@ -25,7 +25,6 @@ #define __XEN_MEM_EVENT_H__ -#include "spinlock.h" #include "xc.h" #include <xc_private.h> @@ -33,9 +32,6 @@ #include <xen/mem_event.h> -#define mem_event_ring_lock_init(_m) spin_lock_init(&(_m)->ring_lock) -#define mem_event_ring_lock(_m) spin_lock(&(_m)->ring_lock) -#define mem_event_ring_unlock(_m) spin_unlock(&(_m)->ring_lock) typedef struct mem_event { @@ -45,7 +41,6 @@ typedef struct mem_event { mem_event_back_ring_t back_ring; mem_event_shared_page_t *shared_page; void *ring_page; - spinlock_t ring_lock; } mem_event_t; diff --git a/tools/xenpaging/spinlock.h b/tools/xenpaging/spinlock.h deleted file mode 100644 index 4f16292b01..0000000000 --- a/tools/xenpaging/spinlock.h +++ /dev/null @@ -1,69 +0,0 @@ -/****************************************************************************** - * tools/xenpaging/spinlock.h - * - * Spinlock implementation. - * - * Copyright (c) 2009 Citrix Systems, Inc. (Patrick Colp) - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - - -#ifndef __SPINLOCK_H__ -#define __SPINLOCK_H__ - - -#include "bitops.h" - - -#define SPIN_LOCK_UNLOCKED 0 - - -typedef int spinlock_t; - - -static inline void spin_lock(spinlock_t *lock) -{ - while ( test_and_set_bit(1, lock) ); -} - -static inline void spin_lock_init(spinlock_t *lock) -{ - *lock = SPIN_LOCK_UNLOCKED; -} - -static inline void spin_unlock(spinlock_t *lock) -{ - *lock = SPIN_LOCK_UNLOCKED; -} - -static inline int spin_trylock(spinlock_t *lock) -{ - return !test_and_set_bit(1, lock); -} - - -#endif // __SPINLOCK_H__ - - -/* - * Local variables: - * mode: C - * c-set-style: "BSD" - * c-basic-offset: 4 - * tab-width: 4 - * indent-tabs-mode: nil - * End: - */ diff --git a/tools/xenpaging/xenpaging.c b/tools/xenpaging/xenpaging.c index cbf75085f6..ec10b36923 100644 --- a/tools/xenpaging/xenpaging.c +++ b/tools/xenpaging/xenpaging.c @@ -32,7 +32,6 @@ #include <xen/mem_event.h> #include "bitops.h" -#include "spinlock.h" #include "file_ops.h" #include "xc.h" @@ -127,9 +126,6 @@ static xenpaging_t *xenpaging_init(domid_t domain_id) BACK_RING_INIT(&paging->mem_event.back_ring, (mem_event_sring_t *)paging->mem_event.ring_page, PAGE_SIZE); - - /* Initialise lock */ - mem_event_ring_lock_init(&paging->mem_event); /* Initialise Xen */ rc = xc_mem_event_enable(xch, paging->mem_event.domain_id, @@ -302,8 +298,6 @@ static int get_request(mem_event_t *mem_event, mem_event_request_t *req) mem_event_back_ring_t *back_ring; RING_IDX req_cons; - mem_event_ring_lock(mem_event); - back_ring = &mem_event->back_ring; req_cons = back_ring->req_cons; @@ -315,8 +309,6 @@ static int get_request(mem_event_t *mem_event, mem_event_request_t *req) back_ring->req_cons = req_cons; back_ring->sring->req_event = req_cons + 1; - mem_event_ring_unlock(mem_event); - return 0; } @@ -325,8 +317,6 @@ static int put_response(mem_event_t *mem_event, mem_event_response_t *rsp) mem_event_back_ring_t *back_ring; RING_IDX rsp_prod; - mem_event_ring_lock(mem_event); - back_ring = &mem_event->back_ring; rsp_prod = back_ring->rsp_prod_pvt; @@ -338,8 +328,6 @@ static int put_response(mem_event_t *mem_event, mem_event_response_t *rsp) back_ring->rsp_prod_pvt = rsp_prod; RING_PUSH_RESPONSES(back_ring); - mem_event_ring_unlock(mem_event); - return 0; } diff --git a/tools/xenpaging/xenpaging.h b/tools/xenpaging/xenpaging.h index f4ebcefca8..d521b9ece1 100644 --- a/tools/xenpaging/xenpaging.h +++ b/tools/xenpaging/xenpaging.h @@ -25,7 +25,6 @@ #define __XEN_PAGING2_H__ -#include "spinlock.h" #include "xc.h" #include <xc_private.h> |