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ieee1394: csr1212: proper refcounting

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At least since nodemgr got rid of coarse global locking, accesses to
struct csr1212_keyval's reference counter should be atomic and coupled
with proper barriers.  Also, calls to csr1212_keep_keyval(kv) should
occur before kv is being used.

(We probably should convert refcnt to struct kref, but how to keep
csr1212_destroy_keyval's implementation non-recursively then?)

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2007-09-15 14:50:25 +02:00
parent 638d5bb816
commit 17a19b795e
3 changed files with 36 additions and 31 deletions
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57
drivers/ieee1394/csr1212.c
View file

@ -218,12 +218,10 @@ static struct csr1212_keyval *csr1212_new_keyval(u8 type, u8 key)
if (!kv) if (!kv)
return NULL; return NULL;
atomic_set(&kv->refcnt, 1);
kv->key.type = type; kv->key.type = type;
kv->key.id = key; kv->key.id = key;
kv->associate = NULL; kv->associate = NULL;
kv->refcnt = 1;
kv->next = NULL; kv->next = NULL;
kv->prev = NULL; kv->prev = NULL;
kv->offset = 0; kv->offset = 0;
@ -326,12 +324,13 @@ void csr1212_associate_keyval(struct csr1212_keyval *kv,
if (kv->associate) if (kv->associate)
csr1212_release_keyval(kv->associate); csr1212_release_keyval(kv->associate);
associate->refcnt++; csr1212_keep_keyval(associate);
kv->associate = associate; kv->associate = associate;
} }
int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir, static int __csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
struct csr1212_keyval *kv) struct csr1212_keyval *kv,
bool keep_keyval)
{ {
struct csr1212_dentry *dentry; struct csr1212_dentry *dentry;
@ -341,10 +340,10 @@ int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
if (!dentry) if (!dentry)
return -ENOMEM; return -ENOMEM;
if (keep_keyval)
csr1212_keep_keyval(kv);
dentry->kv = kv; dentry->kv = kv;
kv->refcnt++;
dentry->next = NULL; dentry->next = NULL;
dentry->prev = dir->value.directory.dentries_tail; dentry->prev = dir->value.directory.dentries_tail;
@ -358,6 +357,12 @@ int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
return CSR1212_SUCCESS; return CSR1212_SUCCESS;
} }
int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
struct csr1212_keyval *kv)
{
return __csr1212_attach_keyval_to_directory(dir, kv, true);
}
#define CSR1212_DESCRIPTOR_LEAF_DATA(kv) \ #define CSR1212_DESCRIPTOR_LEAF_DATA(kv) \
(&((kv)->value.leaf.data[1])) (&((kv)->value.leaf.data[1]))
@ -483,15 +488,18 @@ void csr1212_detach_keyval_from_directory(struct csr1212_keyval *dir,
/* This function is used to free the memory taken by a keyval. If the given /* This function is used to free the memory taken by a keyval. If the given
* keyval is a directory type, then any keyvals contained in that directory * keyval is a directory type, then any keyvals contained in that directory
* will be destroyed as well if their respective refcnts are 0. By means of * will be destroyed as well if noone holds a reference on them. By means of
* list manipulation, this routine will descend a directory structure in a * list manipulation, this routine will descend a directory structure in a
* non-recursive manner. */ * non-recursive manner. */
static void csr1212_destroy_keyval(struct csr1212_keyval *kv) void csr1212_release_keyval(struct csr1212_keyval *kv)
{ {
struct csr1212_keyval *k, *a; struct csr1212_keyval *k, *a;
struct csr1212_dentry dentry; struct csr1212_dentry dentry;
struct csr1212_dentry *head, *tail; struct csr1212_dentry *head, *tail;
if (!atomic_dec_and_test(&kv->refcnt))
return;
dentry.kv = kv; dentry.kv = kv;
dentry.next = NULL; dentry.next = NULL;
dentry.prev = NULL; dentry.prev = NULL;
@ -503,9 +511,8 @@ static void csr1212_destroy_keyval(struct csr1212_keyval *kv)
k = head->kv; k = head->kv;
while (k) { while (k) {
k->refcnt--; /* must not dec_and_test kv->refcnt again */
if (k != kv && !atomic_dec_and_test(&k->refcnt))
if (k->refcnt > 0)
break; break;
a = k->associate; a = k->associate;
@ -536,14 +543,6 @@ static void csr1212_destroy_keyval(struct csr1212_keyval *kv)
} }
} }
void csr1212_release_keyval(struct csr1212_keyval *kv)
{
if (kv->refcnt > 1)
kv->refcnt--;
else
csr1212_destroy_keyval(kv);
}
void csr1212_destroy_csr(struct csr1212_csr *csr) void csr1212_destroy_csr(struct csr1212_csr *csr)
{ {
struct csr1212_csr_rom_cache *c, *oc; struct csr1212_csr_rom_cache *c, *oc;
@ -1126,6 +1125,7 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
int ret = CSR1212_SUCCESS; int ret = CSR1212_SUCCESS;
struct csr1212_keyval *k = NULL; struct csr1212_keyval *k = NULL;
u32 offset; u32 offset;
bool keep_keyval = true;
switch (CSR1212_KV_KEY_TYPE(ki)) { switch (CSR1212_KV_KEY_TYPE(ki)) {
case CSR1212_KV_TYPE_IMMEDIATE: case CSR1212_KV_TYPE_IMMEDIATE:
@ -1135,8 +1135,8 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
ret = -ENOMEM; ret = -ENOMEM;
goto out; goto out;
} }
/* Don't keep local reference when parsing. */
k->refcnt = 0; /* Don't keep local reference when parsing. */ keep_keyval = false;
break; break;
case CSR1212_KV_TYPE_CSR_OFFSET: case CSR1212_KV_TYPE_CSR_OFFSET:
@ -1146,7 +1146,8 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
ret = -ENOMEM; ret = -ENOMEM;
goto out; goto out;
} }
k->refcnt = 0; /* Don't keep local reference when parsing. */ /* Don't keep local reference when parsing. */
keep_keyval = false;
break; break;
default: default:
@ -1174,8 +1175,10 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
ret = -ENOMEM; ret = -ENOMEM;
goto out; goto out;
} }
k->refcnt = 0; /* Don't keep local reference when parsing. */ /* Don't keep local reference when parsing. */
k->valid = 0; /* Contents not read yet so it's not valid. */ keep_keyval = false;
/* Contents not read yet so it's not valid. */
k->valid = 0;
k->offset = offset; k->offset = offset;
k->prev = dir; k->prev = dir;
@ -1183,7 +1186,7 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
dir->next->prev = k; dir->next->prev = k;
dir->next = k; dir->next = k;
} }
ret = csr1212_attach_keyval_to_directory(dir, k); ret = __csr1212_attach_keyval_to_directory(dir, k, keep_keyval);
out: out:
if (ret != CSR1212_SUCCESS && k != NULL) if (ret != CSR1212_SUCCESS && k != NULL)
free_keyval(k); free_keyval(k);

6
drivers/ieee1394/csr1212.h
View file

@ -32,6 +32,7 @@
#include <linux/types.h> #include <linux/types.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <asm/atomic.h>
#define CSR1212_MALLOC(size) kmalloc((size), GFP_KERNEL) #define CSR1212_MALLOC(size) kmalloc((size), GFP_KERNEL)
#define CSR1212_FREE(ptr) kfree(ptr) #define CSR1212_FREE(ptr) kfree(ptr)
@ -149,7 +150,7 @@ struct csr1212_keyval {
struct csr1212_directory directory; struct csr1212_directory directory;
} value; } value;
struct csr1212_keyval *associate; struct csr1212_keyval *associate;
int refcnt; atomic_t refcnt;
/* used in generating and/or parsing CSR image */ /* used in generating and/or parsing CSR image */
struct csr1212_keyval *next, *prev; /* flat list of CSR elements */ struct csr1212_keyval *next, *prev; /* flat list of CSR elements */
@ -350,7 +351,8 @@ csr1212_get_keyval(struct csr1212_csr *csr, struct csr1212_keyval *kv);
* need for code to retain a keyval that has been parsed. */ * need for code to retain a keyval that has been parsed. */
static inline void csr1212_keep_keyval(struct csr1212_keyval *kv) static inline void csr1212_keep_keyval(struct csr1212_keyval *kv)
{ {
kv->refcnt++; atomic_inc(&kv->refcnt);
smp_mb__after_atomic_inc();
} }

4
drivers/ieee1394/nodemgr.c
View file

@ -1014,13 +1014,13 @@ static struct unit_directory *nodemgr_process_unit_directory
CSR1212_TEXTUAL_DESCRIPTOR_LEAF_LANGUAGE(kv) == 0) { CSR1212_TEXTUAL_DESCRIPTOR_LEAF_LANGUAGE(kv) == 0) {
switch (last_key_id) { switch (last_key_id) {
case CSR1212_KV_ID_VENDOR: case CSR1212_KV_ID_VENDOR:
ud->vendor_name_kv = kv;
csr1212_keep_keyval(kv); csr1212_keep_keyval(kv);
ud->vendor_name_kv = kv;
break; break;
case CSR1212_KV_ID_MODEL: case CSR1212_KV_ID_MODEL:
ud->model_name_kv = kv;
csr1212_keep_keyval(kv); csr1212_keep_keyval(kv);
ud->model_name_kv = kv;
break; break;
} }