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pool: do poolcheck when free nodes get corrupted instead of assert

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doing poolcheck should give us better context to figure out
what memory blocks / owners corrupted the blocks after free.

this is for hunting down a memory corruption seen in connection
with usb serial.
This commit is contained in:
cinap_lenrek 2013-05-31 18:55:01 +02:00
parent a84c51a1e3
commit 2a94e1fc19
1 changed files with 28 additions and 30 deletions
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58
sys/src/libc/port/pool.c
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@ -159,7 +159,6 @@ static void poolnewarena(Pool*, ulong);
static void* poolreallocl(Pool*, void*, ulong);
static Free* treedelete(Free*, Free*);
static Free* treeinsert(Free*, Free*);
static Free* treelookup(Free*, ulong);
static Free* treelookupgt(Free*, ulong);
/*
@ -230,30 +229,21 @@ checktree(Free *t, int a, int b)
static Free**
ltreewalk(Free **t, ulong size)
{
assert(t != nil /* ltreewalk */);
Free *f;
for(;;) {
if(*t == nil)
f = *t;
if(f == nil || f->magic != FREE_MAGIC)
return t;
assert((*t)->magic == FREE_MAGIC);
if(size == (*t)->size)
if(size == f->size)
return t;
if(size < (*t)->size)
t = &(*t)->left;
if(size < f->size)
t = &f->left;
else
t = &(*t)->right;
t = &f->right;
}
}
/* treelookup: find node in tree with size == size */
static Free*
treelookup(Free *t, ulong size)
{
return *ltreewalk(&t, size);
}
/* treeinsert: insert node into tree */
static Free*
treeinsert(Free *tree, Free *node)
@ -263,11 +253,11 @@ treeinsert(Free *tree, Free *node)
assert(node != nil /* treeinsert */);
loc = ltreewalk(&tree, node->size);
if(*loc == nil) {
repl = *loc;
if(repl == nil || repl->magic != FREE_MAGIC) {
node->left = nil;
node->right = nil;
} else { /* replace existing node */
repl = *loc;
node->left = repl->left;
node->right = repl->right;
}
@ -284,7 +274,8 @@ treedelete(Free *tree, Free *node)
assert(node != nil /* treedelete */);
loc = ltreewalk(&tree, node->size);
assert(*loc == node);
if(*loc != node || node->magic != FREE_MAGIC)
return tree; /* free nodes corrupted */
if(node->left == nil)
*loc = node->right;
@ -300,7 +291,6 @@ treedelete(Free *tree, Free *node)
succ->right = node->right;
*loc = succ;
}
node->left = node->right = Poison;
return tree;
}
@ -313,7 +303,7 @@ treelookupgt(Free *t, ulong size)
lastgood = nil;
for(;;) {
if(t == nil)
if(t == nil || t->magic != FREE_MAGIC)
return lastgood;
if(size == t->size)
return t;
@ -387,6 +377,11 @@ pooladd(Pool *p, Alloc *anode)
node->magic = FREE_MAGIC;
parent = ltreewalk(&p->freeroot, node->size);
olst = *parent;
if(olst != nil && olst->magic != FREE_MAGIC){
/* corruption of free nodes */
poolcheckl(p);
olst = *parent = nil;
}
lst = listadd(olst, node);
if(olst != lst) /* need to update tree */
*parent = treeinsert(*parent, lst);
@ -403,14 +398,17 @@ pooldel(Pool *p, Free *node)
parent = ltreewalk(&p->freeroot, node->size);
olst = *parent;
assert(olst != nil /* pooldel */);
lst = listdelete(olst, node);
if(lst == nil)
*parent = treedelete(*parent, olst);
else if(lst != olst)
*parent = treeinsert(*parent, lst);
if(olst == nil || olst->magic != FREE_MAGIC){
/* corruption of free nodes */
poolcheckl(p);
*parent = nil;
} else {
lst = listdelete(olst, node);
if(lst == nil)
*parent = treedelete(*parent, olst);
else if(lst != olst)
*parent = treeinsert(*parent, lst);
}
node->left = node->right = Poison;
p->curfree -= node->size;