Sebastian Lackner : ntdll: Use lockfree implementation for get_cached_fd.
Alexandre Julliard
julliard at wine.codeweavers.com
Mon May 4 07:58:53 CDT 2015
Module: wine
Branch: master
Commit: 40c912b4bef45099d465ddb9a7cb16f33ec4ed3c
URL: http://source.winehq.org/git/wine.git/?a=commit;h=40c912b4bef45099d465ddb9a7cb16f33ec4ed3c
Author: Sebastian Lackner <sebastian at fds-team.de>
Date: Thu Apr 30 04:22:53 2015 +0200
ntdll: Use lockfree implementation for get_cached_fd.
---
dlls/ntdll/server.c | 105 ++++++++++++++++++++++++++++++++++------------------
1 file changed, 68 insertions(+), 37 deletions(-)
diff --git a/dlls/ntdll/server.c b/dlls/ntdll/server.c
index 69d01be..652a1aa 100644
--- a/dlls/ntdll/server.c
+++ b/dlls/ntdll/server.c
@@ -75,6 +75,8 @@
#include "ntstatus.h"
#define WIN32_NO_STATUS
+#include "windef.h"
+#include "winnt.h"
#include "wine/library.h"
#include "wine/server.h"
#include "wine/debug.h"
@@ -126,6 +128,17 @@ static RTL_CRITICAL_SECTION_DEBUG critsect_debug =
};
static RTL_CRITICAL_SECTION fd_cache_section = { &critsect_debug, -1, 0, 0, 0, 0 };
+/* atomically exchange a 64-bit value */
+static inline LONG64 interlocked_xchg64( LONG64 *dest, LONG64 val )
+{
+#ifdef _WIN64
+ return (LONG64)interlocked_xchg_ptr( (void **)dest, (void *)val );
+#else
+ LONG64 tmp = *dest;
+ while (interlocked_cmpxchg64( dest, val, tmp ) != tmp) tmp = *dest;
+ return tmp;
+#endif
+}
#ifdef __GNUC__
static void fatal_error( const char *err, ... ) __attribute__((noreturn, format(printf,1,2)));
@@ -790,19 +803,27 @@ static int receive_fd( obj_handle_t *handle )
/***********************************************************************/
/* fd cache support */
-struct fd_cache_entry
+#include "pshpack1.h"
+union fd_cache_entry
{
- int fd;
- enum server_fd_type type : 5;
- unsigned int access : 3;
- unsigned int options : 24;
+ LONG64 data;
+ struct
+ {
+ int fd;
+ enum server_fd_type type : 5;
+ unsigned int access : 3;
+ unsigned int options : 24;
+ } s;
};
+#include "poppack.h"
-#define FD_CACHE_BLOCK_SIZE (65536 / sizeof(struct fd_cache_entry))
+C_ASSERT( sizeof(union fd_cache_entry) == sizeof(LONG64) );
+
+#define FD_CACHE_BLOCK_SIZE (65536 / sizeof(union fd_cache_entry))
#define FD_CACHE_ENTRIES 128
-static struct fd_cache_entry *fd_cache[FD_CACHE_ENTRIES];
-static struct fd_cache_entry fd_cache_initial_block[FD_CACHE_BLOCK_SIZE];
+static union fd_cache_entry *fd_cache[FD_CACHE_ENTRIES];
+static union fd_cache_entry fd_cache_initial_block[FD_CACHE_BLOCK_SIZE];
static inline unsigned int handle_to_index( HANDLE handle, unsigned int *entry )
{
@@ -821,6 +842,7 @@ static BOOL add_fd_to_cache( HANDLE handle, int fd, enum server_fd_type type,
unsigned int access, unsigned int options )
{
unsigned int entry, idx = handle_to_index( handle, &entry );
+ union fd_cache_entry cache;
if (entry >= FD_CACHE_ENTRIES)
{
@@ -833,26 +855,26 @@ static BOOL add_fd_to_cache( HANDLE handle, int fd, enum server_fd_type type,
if (!entry) fd_cache[0] = fd_cache_initial_block;
else
{
- void *ptr = wine_anon_mmap( NULL, FD_CACHE_BLOCK_SIZE * sizeof(struct fd_cache_entry),
+ void *ptr = wine_anon_mmap( NULL, FD_CACHE_BLOCK_SIZE * sizeof(union fd_cache_entry),
PROT_READ | PROT_WRITE, 0 );
if (ptr == MAP_FAILED) return FALSE;
fd_cache[entry] = ptr;
}
}
+
/* store fd+1 so that 0 can be used as the unset value */
- fd = interlocked_xchg( &fd_cache[entry][idx].fd, fd + 1 );
- fd_cache[entry][idx].type = type;
- fd_cache[entry][idx].access = access;
- fd_cache[entry][idx].options = options;
- assert( !fd );
+ cache.s.fd = fd + 1;
+ cache.s.type = type;
+ cache.s.access = access;
+ cache.s.options = options;
+ cache.data = interlocked_xchg64( &fd_cache[entry][idx].data, cache.data );
+ assert( !cache.s.fd );
return TRUE;
}
/***********************************************************************
* get_cached_fd
- *
- * Caller must hold fd_cache_section.
*/
static inline int get_cached_fd( HANDLE handle, enum server_fd_type *type,
unsigned int *access, unsigned int *options )
@@ -862,10 +884,12 @@ static inline int get_cached_fd( HANDLE handle, enum server_fd_type *type,
if (entry < FD_CACHE_ENTRIES && fd_cache[entry])
{
- fd = fd_cache[entry][idx].fd - 1;
- if (type) *type = fd_cache[entry][idx].type;
- if (access) *access = fd_cache[entry][idx].access;
- if (options) *options = fd_cache[entry][idx].options;
+ union fd_cache_entry cache;
+ cache.data = interlocked_cmpxchg64( &fd_cache[entry][idx].data, 0, 0 );
+ fd = cache.s.fd - 1;
+ if (type) *type = cache.s.type;
+ if (access) *access = cache.s.access;
+ if (options) *options = cache.s.options;
}
return fd;
}
@@ -880,7 +904,11 @@ int server_remove_fd_from_cache( HANDLE handle )
int fd = -1;
if (entry < FD_CACHE_ENTRIES && fd_cache[entry])
- fd = interlocked_xchg( &fd_cache[entry][idx].fd, 0 ) - 1;
+ {
+ union fd_cache_entry cache;
+ cache.data = interlocked_xchg64( &fd_cache[entry][idx].data, 0 );
+ fd = cache.s.fd - 1;
+ }
return fd;
}
@@ -903,33 +931,36 @@ int server_get_unix_fd( HANDLE handle, unsigned int wanted_access, int *unix_fd,
*needs_close = 0;
wanted_access &= FILE_READ_DATA | FILE_WRITE_DATA | FILE_APPEND_DATA;
- server_enter_uninterrupted_section( &fd_cache_section, &sigset );
-
fd = get_cached_fd( handle, type, &access, options );
if (fd != -1) goto done;
- SERVER_START_REQ( get_handle_fd )
+ server_enter_uninterrupted_section( &fd_cache_section, &sigset );
+ fd = get_cached_fd( handle, type, &access, options );
+ if (fd == -1)
{
- req->handle = wine_server_obj_handle( handle );
- if (!(ret = wine_server_call( req )))
+ SERVER_START_REQ( get_handle_fd )
{
- if (type) *type = reply->type;
- if (options) *options = reply->options;
- access = reply->access;
- if ((fd = receive_fd( &fd_handle )) != -1)
+ req->handle = wine_server_obj_handle( handle );
+ if (!(ret = wine_server_call( req )))
{
- assert( wine_server_ptr_handle(fd_handle) == handle );
- *needs_close = (!reply->cacheable ||
- !add_fd_to_cache( handle, fd, reply->type,
- reply->access, reply->options ));
+ if (type) *type = reply->type;
+ if (options) *options = reply->options;
+ access = reply->access;
+ if ((fd = receive_fd( &fd_handle )) != -1)
+ {
+ assert( wine_server_ptr_handle(fd_handle) == handle );
+ *needs_close = (!reply->cacheable ||
+ !add_fd_to_cache( handle, fd, reply->type,
+ reply->access, reply->options ));
+ }
+ else ret = STATUS_TOO_MANY_OPENED_FILES;
}
- else ret = STATUS_TOO_MANY_OPENED_FILES;
}
+ SERVER_END_REQ;
}
- SERVER_END_REQ;
+ server_leave_uninterrupted_section( &fd_cache_section, &sigset );
done:
- server_leave_uninterrupted_section( &fd_cache_section, &sigset );
if (!ret && ((access & wanted_access) != wanted_access))
{
ret = STATUS_ACCESS_DENIED;
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