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author | Tianon Gravi <admwiggin@gmail.com> | 2015-01-15 11:54:00 -0700 |
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committer | Tianon Gravi <admwiggin@gmail.com> | 2015-01-15 11:54:00 -0700 |
commit | f154da9e12608589e8d5f0508f908a0c3e88a1bb (patch) | |
tree | f8255d51e10c6f1e0ed69702200b966c9556a431 /src/runtime/lfstack.c | |
parent | 8d8329ed5dfb9622c82a9fbec6fd99a580f9c9f6 (diff) | |
download | golang-f154da9e12608589e8d5f0508f908a0c3e88a1bb.tar.gz |
Imported Upstream version 1.4upstream/1.4
Diffstat (limited to 'src/runtime/lfstack.c')
-rw-r--r-- | src/runtime/lfstack.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/runtime/lfstack.c b/src/runtime/lfstack.c new file mode 100644 index 000000000..57e0af282 --- /dev/null +++ b/src/runtime/lfstack.c @@ -0,0 +1,87 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Lock-free stack. +// The following code runs only on g0 stack. + +#include "runtime.h" +#include "arch_GOARCH.h" + +#ifdef _64BIT +// Amd64 uses 48-bit virtual addresses, 47-th bit is used as kernel/user flag. +// So we use 17msb of pointers as ABA counter. +# define PTR_BITS 47 +#else +# define PTR_BITS 32 +#endif +#define PTR_MASK ((1ull<<PTR_BITS)-1) +#define CNT_MASK (0ull-1) + +#ifdef _64BIT +#ifdef GOOS_solaris +// SPARC64 and Solaris on AMD64 uses all 64 bits of virtual addresses. +// Use low-order three bits as ABA counter. +// http://docs.oracle.com/cd/E19120-01/open.solaris/816-5138/6mba6ua5p/index.html +#undef PTR_BITS +#undef CNT_MASK +#undef PTR_MASK +#define PTR_BITS 0 +#define CNT_MASK 7 +#define PTR_MASK ((0ull-1)<<3) +#endif +#endif + +void +runtime·lfstackpush(uint64 *head, LFNode *node) +{ + uint64 old, new; + + if((uintptr)node != ((uintptr)node&PTR_MASK)) { + runtime·printf("p=%p\n", node); + runtime·throw("runtime·lfstackpush: invalid pointer"); + } + + node->pushcnt++; + new = (uint64)(uintptr)node|(((uint64)node->pushcnt&CNT_MASK)<<PTR_BITS); + for(;;) { + old = runtime·atomicload64(head); + node->next = (LFNode*)(uintptr)(old&PTR_MASK); + if(runtime·cas64(head, old, new)) + break; + } +} + +LFNode* +runtime·lfstackpop(uint64 *head) +{ + LFNode *node, *node2; + uint64 old, new; + + for(;;) { + old = runtime·atomicload64(head); + if(old == 0) + return nil; + node = (LFNode*)(uintptr)(old&PTR_MASK); + node2 = runtime·atomicloadp(&node->next); + new = 0; + if(node2 != nil) + new = (uint64)(uintptr)node2|(((uint64)node2->pushcnt&CNT_MASK)<<PTR_BITS); + if(runtime·cas64(head, old, new)) + return node; + } +} + +void +runtime·lfstackpush_m(void) +{ + runtime·lfstackpush(g->m->ptrarg[0], g->m->ptrarg[1]); + g->m->ptrarg[0] = nil; + g->m->ptrarg[1] = nil; +} + +void +runtime·lfstackpop_m(void) +{ + g->m->ptrarg[0] = runtime·lfstackpop(g->m->ptrarg[0]); +} |