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* [newlib-cygwin] Cygwin: mmap: use SRWLOCK instead of muto
@ 2022-08-24 9:20 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2022-08-24 9:20 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=ee54cabad9c9fcc45275551dae7bd9fc9da78f83
commit ee54cabad9c9fcc45275551dae7bd9fc9da78f83
Author: Corinna Vinschen <corinna@vinschen.de>
Date: Tue Aug 23 11:14:12 2022 +0200
Cygwin: mmap: use SRWLOCK instead of muto
To reduce thread contention, use reader/writer locks as required.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/mm/mmap.cc | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
diff --git a/winsup/cygwin/mm/mmap.cc b/winsup/cygwin/mm/mmap.cc
index c33342bc3..332c015a7 100644
--- a/winsup/cygwin/mm/mmap.cc
+++ b/winsup/cygwin/mm/mmap.cc
@@ -48,9 +48,11 @@ details. */
static fhandler_dev_zero fh_anonymous;
/* Used for thread synchronization while accessing mmap bookkeeping lists. */
-static NO_COPY muto mmap_guard;
-#define LIST_LOCK() (mmap_guard.init ("mmap_guard")->acquire ())
-#define LIST_UNLOCK() (mmap_guard.release ())
+static NO_COPY SRWLOCK mmap_lock = SRWLOCK_INIT;
+#define LIST_WRITE_LOCK() (AcquireSRWLockExclusive (&mmap_lock))
+#define LIST_WRITE_UNLOCK() (ReleaseSRWLockExclusive (&mmap_lock))
+#define LIST_READ_LOCK() (AcquireSRWLockShared (&mmap_lock))
+#define LIST_READ_UNLOCK() (ReleaseSRWLockShared (&mmap_lock))
/* Small helpers to avoid having lots of flag bit tests in the code. */
static inline bool
@@ -703,12 +705,12 @@ is_mmapped_region (caddr_t start_addr, caddr_t end_address)
{
size_t len = end_address - start_addr;
- LIST_LOCK ();
+ LIST_READ_LOCK ();
mmap_list *map_list = mmapped_areas.get_list_by_fd (-1, NULL);
if (!map_list)
{
- LIST_UNLOCK ();
+ LIST_READ_UNLOCK ();
return false;
}
@@ -725,7 +727,7 @@ is_mmapped_region (caddr_t start_addr, caddr_t end_address)
break;
}
}
- LIST_UNLOCK ();
+ LIST_READ_UNLOCK ();
return ret;
}
@@ -753,7 +755,7 @@ mmap_is_attached_or_noreserve (void *addr, size_t len)
{
mmap_region_status ret = MMAP_NONE;
- LIST_LOCK ();
+ LIST_READ_LOCK ();
mmap_list *map_list = mmapped_areas.get_list_by_fd (-1, NULL);
const size_t pagesize = wincap.allocation_granularity ();
@@ -800,7 +802,7 @@ mmap_is_attached_or_noreserve (void *addr, size_t len)
}
}
out:
- LIST_UNLOCK ();
+ LIST_READ_UNLOCK ();
return ret;
}
@@ -1043,7 +1045,7 @@ go_ahead:
if (noreserve (flags) && (!anonymous (flags) || !priv (flags)))
flags &= ~MAP_NORESERVE;
- LIST_LOCK ();
+ LIST_WRITE_LOCK ();
map_list = mmapped_areas.get_list_by_fd (fd, &st);
/* Test if an existing anonymous mapping can be recycled. */
@@ -1096,7 +1098,7 @@ go_ahead:
ret = base;
out_with_unlock:
- LIST_UNLOCK ();
+ LIST_WRITE_UNLOCK ();
out:
@@ -1144,7 +1146,7 @@ munmap (void *addr, size_t len)
}
len = roundup2 (len, pagesize);
- LIST_LOCK ();
+ LIST_WRITE_LOCK ();
/* Iterate over maps, unmap pages between addr and addr+len in all maps. */
mmap_list *map_list, *next_map_list;
@@ -1180,7 +1182,7 @@ munmap (void *addr, size_t len)
}
}
- LIST_UNLOCK ();
+ LIST_WRITE_UNLOCK ();
syscall_printf ("0 = munmap(): %p", addr);
return 0;
}
@@ -1197,19 +1199,20 @@ msync (void *addr, size_t len, int flags)
pthread_testcancel ();
- LIST_LOCK ();
-
if (((uintptr_t) addr % wincap.allocation_granularity ())
|| (flags & ~(MS_ASYNC | MS_SYNC | MS_INVALIDATE))
|| ((flags & (MS_ASYNC | MS_SYNC)) == (MS_ASYNC | MS_SYNC)))
{
set_errno (EINVAL);
- goto out;
+ syscall_printf ("%R = msync()", ret);
+ return ret;
}
#if 0 /* If I only knew why I did that... */
len = roundup2 (len, wincap.allocation_granularity ());
#endif
+ LIST_READ_LOCK ();
+
/* Iterate over maps, looking for the mmapped area. Error if not found. */
LIST_FOREACH (map_list, &mmapped_areas.lists, ml_next)
{
@@ -1239,7 +1242,7 @@ msync (void *addr, size_t len, int flags)
set_errno (ENOMEM);
out:
- LIST_UNLOCK ();
+ LIST_READ_UNLOCK ();
syscall_printf ("%R = msync()", ret);
return ret;
}
@@ -1265,7 +1268,7 @@ mprotect (void *addr, size_t len, int prot)
}
len = roundup2 (len, pagesize);
- LIST_LOCK ();
+ LIST_WRITE_LOCK ();
/* Iterate over maps, protect pages between addr and addr+len in all maps. */
mmap_list *map_list;
@@ -1300,7 +1303,7 @@ mprotect (void *addr, size_t len, int prot)
}
}
- LIST_UNLOCK ();
+ LIST_WRITE_UNLOCK ();
if (!in_mapped)
{
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