Commit 17a19b79 authored by Stefan Richter's avatar Stefan Richter
Browse files

ieee1394: csr1212: proper refcounting 



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: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent 638d5bb8

drivers/ieee1394/csr1212.c

+30 −27
Original line number Diff line number Diff line
@@ -218,12 +218,10 @@ static struct csr1212_keyval *csr1212_new_keyval(u8 type, u8 key) 
	if (!kv)

		return NULL;



	atomic_set(&kv->refcnt, 1);

	kv->key.type = type;

	kv->key.id = key;



	kv->associate = NULL;

	kv->refcnt = 1;



	kv->next = NULL;

	kv->prev = NULL;

	kv->offset = 0;
@@ -326,12 +324,13 @@ void csr1212_associate_keyval(struct csr1212_keyval *kv, 
	if (kv->associate)

		csr1212_release_keyval(kv->associate);



	associate->refcnt++;

	csr1212_keep_keyval(associate);

	kv->associate = associate;

}



int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,

				       struct csr1212_keyval *kv)

static int __csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,

						struct csr1212_keyval *kv,

						bool keep_keyval)

{

	struct csr1212_dentry *dentry;
@@ -341,10 +340,10 @@ int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir, 
	if (!dentry)

		return -ENOMEM;



	if (keep_keyval)

		csr1212_keep_keyval(kv);

	dentry->kv = kv;



	kv->refcnt++;



	dentry->next = NULL;

	dentry->prev = dir->value.directory.dentries_tail;
@@ -358,6 +357,12 @@ int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir, 
	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) \

	(&((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

 * 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

 * 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_dentry dentry;

	struct csr1212_dentry *head, *tail;



	if (!atomic_dec_and_test(&kv->refcnt))

		return;



	dentry.kv = kv;

	dentry.next = NULL;

	dentry.prev = NULL;
@@ -503,9 +511,8 @@ static void csr1212_destroy_keyval(struct csr1212_keyval *kv) 
		k = head->kv;



		while (k) {

			k->refcnt--;



			if (k->refcnt > 0)

			/* must not dec_and_test kv->refcnt again */

			if (k != kv && !atomic_dec_and_test(&k->refcnt))

				break;



			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)

{

	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;

	struct csr1212_keyval *k = NULL;

	u32 offset;

	bool keep_keyval = true;



	switch (CSR1212_KV_KEY_TYPE(ki)) {

	case CSR1212_KV_TYPE_IMMEDIATE:
@@ -1135,8 +1135,8 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos) 
			ret = -ENOMEM;

			goto out;

		}



		k->refcnt = 0;	/* Don't keep local reference when parsing. */

		/* Don't keep local reference when parsing. */

		keep_keyval = false;

		break;



	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;

			goto out;

		}

		k->refcnt = 0;	/* Don't keep local reference when parsing. */

		/* Don't keep local reference when parsing. */

		keep_keyval = false;

		break;



	default:
@@ -1174,8 +1175,10 @@ csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos) 
			ret = -ENOMEM;

			goto out;

		}

		k->refcnt = 0;	/* Don't keep local reference when parsing. */

		k->valid = 0;	/* Contents not read yet so it's not valid. */

		/* Don't keep local reference when parsing. */

		keep_keyval = false;

		/* Contents not read yet so it's not valid. */

		k->valid = 0;

		k->offset = offset;



		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 = k;

	}

	ret = csr1212_attach_keyval_to_directory(dir, k);

	ret = __csr1212_attach_keyval_to_directory(dir, k, keep_keyval);

out:

	if (ret != CSR1212_SUCCESS && k != NULL)

		free_keyval(k);

drivers/ieee1394/csr1212.h

+4 −2
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 


#include <linux/types.h>

#include <linux/slab.h>

#include <asm/atomic.h>



#define CSR1212_MALLOC(size)	kmalloc((size), GFP_KERNEL)

#define CSR1212_FREE(ptr)	kfree(ptr)
@@ -149,7 +150,7 @@ struct csr1212_keyval { 
		struct csr1212_directory directory;

	} value;

	struct csr1212_keyval *associate;

	int refcnt;

	atomic_t refcnt;



	/* used in generating and/or parsing CSR image */

	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. */

static inline void csr1212_keep_keyval(struct csr1212_keyval *kv)

{

	kv->refcnt++;

	atomic_inc(&kv->refcnt);

	smp_mb__after_atomic_inc();

}

drivers/ieee1394/nodemgr.c

+2 −2
Original line number Diff line number Diff line
@@ -1014,13 +1014,13 @@ static struct unit_directory *nodemgr_process_unit_directory 
			    CSR1212_TEXTUAL_DESCRIPTOR_LEAF_LANGUAGE(kv) == 0) {

				switch (last_key_id) {

				case CSR1212_KV_ID_VENDOR:

					ud->vendor_name_kv = kv;

					csr1212_keep_keyval(kv);

					ud->vendor_name_kv = kv;

					break;



				case CSR1212_KV_ID_MODEL:

					ud->model_name_kv = kv;

					csr1212_keep_keyval(kv);

					ud->model_name_kv = kv;

					break;



				}

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