The Tor Browser / annotate

nsprpub/pr/src/threads/combined/prustack.c@6474c204b198 (annotated)

nsprpub/pr/src/threads/combined/prustack.c

Wed, 31 Dec 2014 06:09:35 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Wed, 31 Dec 2014 06:09:35 +0100
changeset 0
6474c204b198
permissions
-rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

michael@0 1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0 2 /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0 3 * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0 5
michael@0 6 #include "primpl.h"
michael@0 7
michael@0 8 /* List of free stack virtual memory chunks */
michael@0 9 PRLock *_pr_stackLock;
michael@0 10 PRCList _pr_freeStacks = PR_INIT_STATIC_CLIST(&_pr_freeStacks);
michael@0 11 PRIntn _pr_numFreeStacks;
michael@0 12 PRIntn _pr_maxFreeStacks = 4;
michael@0 13
michael@0 14 #ifdef DEBUG
michael@0 15 /*
michael@0 16 ** A variable that can be set via the debugger...
michael@0 17 */
michael@0 18 PRBool _pr_debugStacks = PR_FALSE;
michael@0 19 #endif
michael@0 20
michael@0 21 /* How much space to leave between the stacks, at each end */
michael@0 22 #define REDZONE (2 << _pr_pageShift)
michael@0 23
michael@0 24 #define _PR_THREAD_STACK_PTR(_qp) \
michael@0 25 ((PRThreadStack*) ((char*) (_qp) - offsetof(PRThreadStack,links)))
michael@0 26
michael@0 27 void _PR_InitStacks(void)
michael@0 28 {
michael@0 29 _pr_stackLock = PR_NewLock();
michael@0 30 }
michael@0 31
michael@0 32 void _PR_CleanupStacks(void)
michael@0 33 {
michael@0 34 if (_pr_stackLock) {
michael@0 35 PR_DestroyLock(_pr_stackLock);
michael@0 36 _pr_stackLock = NULL;
michael@0 37 }
michael@0 38 }
michael@0 39
michael@0 40 /*
michael@0 41 ** Allocate a stack for a thread.
michael@0 42 */
michael@0 43 PRThreadStack *_PR_NewStack(PRUint32 stackSize)
michael@0 44 {
michael@0 45 PRCList *qp;
michael@0 46 PRThreadStack *ts;
michael@0 47 PRThread *thr;
michael@0 48
michael@0 49 /*
michael@0 50 ** Trim the list of free stacks. Trim it backwards, tossing out the
michael@0 51 ** oldest stack found first (this way more recent stacks have a
michael@0 52 ** chance of being present in the data cache).
michael@0 53 */
michael@0 54 PR_Lock(_pr_stackLock);
michael@0 55 qp = _pr_freeStacks.prev;
michael@0 56 while ((_pr_numFreeStacks > _pr_maxFreeStacks) && (qp != &_pr_freeStacks)) {
michael@0 57 ts = _PR_THREAD_STACK_PTR(qp);
michael@0 58 thr = _PR_THREAD_STACK_TO_PTR(ts);
michael@0 59 qp = qp->prev;
michael@0 60 /*
michael@0 61 * skip stacks which are still being used
michael@0 62 */
michael@0 63 if (thr->no_sched)
michael@0 64 continue;
michael@0 65 PR_REMOVE_LINK(&ts->links);
michael@0 66
michael@0 67 /* Give platform OS to clear out the stack for debugging */
michael@0 68 _PR_MD_CLEAR_STACK(ts);
michael@0 69
michael@0 70 _pr_numFreeStacks--;
michael@0 71 _PR_DestroySegment(ts->seg);
michael@0 72 PR_DELETE(ts);
michael@0 73 }
michael@0 74
michael@0 75 /*
michael@0 76 ** Find a free thread stack. This searches the list of free'd up
michael@0 77 ** virtually mapped thread stacks.
michael@0 78 */
michael@0 79 qp = _pr_freeStacks.next;
michael@0 80 ts = 0;
michael@0 81 while (qp != &_pr_freeStacks) {
michael@0 82 ts = _PR_THREAD_STACK_PTR(qp);
michael@0 83 thr = _PR_THREAD_STACK_TO_PTR(ts);
michael@0 84 qp = qp->next;
michael@0 85 /*
michael@0 86 * skip stacks which are still being used
michael@0 87 */
michael@0 88 if ((!(thr->no_sched)) && ((ts->allocSize - 2*REDZONE) >= stackSize)) {
michael@0 89 /*
michael@0 90 ** Found a stack that is not in use and is big enough. Change
michael@0 91 ** stackSize to fit it.
michael@0 92 */
michael@0 93 stackSize = ts->allocSize - 2*REDZONE;
michael@0 94 PR_REMOVE_LINK(&ts->links);
michael@0 95 _pr_numFreeStacks--;
michael@0 96 ts->links.next = 0;
michael@0 97 ts->links.prev = 0;
michael@0 98 PR_Unlock(_pr_stackLock);
michael@0 99 goto done;
michael@0 100 }
michael@0 101 ts = 0;
michael@0 102 }
michael@0 103 PR_Unlock(_pr_stackLock);
michael@0 104
michael@0 105 if (!ts) {
michael@0 106 /* Make a new thread stack object. */
michael@0 107 ts = PR_NEWZAP(PRThreadStack);
michael@0 108 if (!ts) {
michael@0 109 return NULL;
michael@0 110 }
michael@0 111
michael@0 112 /*
michael@0 113 ** Assign some of the virtual space to the new stack object. We
michael@0 114 ** may not get that piece of VM, but if nothing else we will
michael@0 115 ** advance the pointer so we don't collide (unless the OS screws
michael@0 116 ** up).
michael@0 117 */
michael@0 118 ts->allocSize = stackSize + 2*REDZONE;
michael@0 119 ts->seg = _PR_NewSegment(ts->allocSize, 0);
michael@0 120 if (!ts->seg) {
michael@0 121 PR_DELETE(ts);
michael@0 122 return NULL;
michael@0 123 }
michael@0 124 }
michael@0 125
michael@0 126 done:
michael@0 127 ts->allocBase = (char*)ts->seg->vaddr;
michael@0 128 ts->flags = _PR_STACK_MAPPED;
michael@0 129 ts->stackSize = stackSize;
michael@0 130
michael@0 131 #ifdef HAVE_STACK_GROWING_UP
michael@0 132 ts->stackTop = ts->allocBase + REDZONE;
michael@0 133 ts->stackBottom = ts->stackTop + stackSize;
michael@0 134 #else
michael@0 135 ts->stackBottom = ts->allocBase + REDZONE;
michael@0 136 ts->stackTop = ts->stackBottom + stackSize;
michael@0 137 #endif
michael@0 138
michael@0 139 PR_LOG(_pr_thread_lm, PR_LOG_NOTICE,
michael@0 140 ("thread stack: base=0x%x limit=0x%x bottom=0x%x top=0x%x\n",
michael@0 141 ts->allocBase, ts->allocBase + ts->allocSize - 1,
michael@0 142 ts->allocBase + REDZONE,
michael@0 143 ts->allocBase + REDZONE + stackSize - 1));
michael@0 144
michael@0 145 _PR_MD_INIT_STACK(ts,REDZONE);
michael@0 146
michael@0 147 return ts;
michael@0 148 }
michael@0 149
michael@0 150 /*
michael@0 151 ** Free the stack for the current thread
michael@0 152 */
michael@0 153 void _PR_FreeStack(PRThreadStack *ts)
michael@0 154 {
michael@0 155 if (!ts) {
michael@0 156 return;
michael@0 157 }
michael@0 158 if (ts->flags & _PR_STACK_PRIMORDIAL) {
michael@0 159 PR_DELETE(ts);
michael@0 160 return;
michael@0 161 }
michael@0 162
michael@0 163 /*
michael@0 164 ** Put the stack on the free list. This is done because we are still
michael@0 165 ** using the stack. Next time a thread is created we will trim the
michael@0 166 ** list down; it's safe to do it then because we will have had to
michael@0 167 ** context switch to a live stack before another thread can be
michael@0 168 ** created.
michael@0 169 */
michael@0 170 PR_Lock(_pr_stackLock);
michael@0 171 PR_APPEND_LINK(&ts->links, _pr_freeStacks.prev);
michael@0 172 _pr_numFreeStacks++;
michael@0 173 PR_Unlock(_pr_stackLock);
michael@0 174 }

Mercurial Repository: The Tor Browser

Europalab SCM Repository Server

mercurial