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block: Mark bdrv_parent_perms_conflict() and callers GRAPH_RDLOCK 
The function reads the parents list, so it needs to hold the graph lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-14-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Kevin Wolf committed Sep 14, 2023
1 parent c363f18 commit f0c088c
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Showing 9 changed files with 66 additions and 26 deletions.
28 changes: 18 additions & 10 deletions block.c
View file
Expand Up @@ -2202,7 +2202,8 @@ static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
return false;
}

static bool bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
static bool GRAPH_RDLOCK
bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
{
BdrvChild *a, *b;
GLOBAL_STATE_CODE();
Expand Down Expand Up @@ -2255,8 +2256,8 @@ static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
* simplest way to satisfy this criteria: use only result of
* bdrv_topological_dfs() or NULL as @list parameter.
*/
static GSList *bdrv_topological_dfs(GSList *list, GHashTable *found,
BlockDriverState *bs)
static GSList * GRAPH_RDLOCK
bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs)
{
BdrvChild *child;
g_autoptr(GHashTable) local_found = NULL;
Expand Down Expand Up @@ -2532,8 +2533,9 @@ static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
* @list is a product of bdrv_topological_dfs() (may be called several times) -
* a topologically sorted subgraph.
*/
static int bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q,
Transaction *tran, Error **errp)
static int GRAPH_RDLOCK
bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
Error **errp)
{
int ret;
BlockDriverState *bs;
Expand All @@ -2560,8 +2562,9 @@ static int bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q,
* topologically sorted. It's not a problem if some node occurs in the @list
* several times.
*/
static int bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q,
Transaction *tran, Error **errp)
static int GRAPH_RDLOCK
bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
Error **errp)
{
g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL);
g_autoptr(GSList) refresh_list = NULL;
Expand Down Expand Up @@ -2621,8 +2624,8 @@ char *bdrv_perm_names(uint64_t perm)


/* @tran is allowed to be NULL. In this case no rollback is possible */
static int bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran,
Error **errp)
static int GRAPH_RDLOCK
bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
{
int ret;
Transaction *local_tran = NULL;
Expand Down Expand Up @@ -3247,7 +3250,6 @@ void bdrv_root_unref_child(BdrvChild *child)
GLOBAL_STATE_CODE();
bdrv_graph_wrlock(NULL);
bdrv_replace_child_noperm(child, NULL);
bdrv_graph_wrunlock();
bdrv_child_free(child);

if (child_bs) {
Expand All @@ -3266,6 +3268,7 @@ void bdrv_root_unref_child(BdrvChild *child)
NULL);
}

bdrv_graph_wrunlock();
bdrv_unref(child_bs);
}

Expand Down Expand Up @@ -4585,7 +4588,10 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
* reconfiguring the fd and that's why it does it in raw_check_perm(), not
* in raw_reopen_prepare() which is called with "old" permissions.
*/
bdrv_graph_rdlock_main_loop();
ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
bdrv_graph_rdunlock_main_loop();

if (ret < 0) {
goto abort;
}
Expand Down Expand Up @@ -6833,6 +6839,7 @@ int bdrv_activate(BlockDriverState *bs, Error **errp)
BdrvDirtyBitmap *bm;

GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();

if (!bs->drv) {
return -ENOMEDIUM;
Expand Down Expand Up @@ -6963,6 +6970,7 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs)
uint64_t cumulative_perms, cumulative_shared_perms;

GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();

if (!bs->drv) {
return -ENOMEDIUM;
Expand Down
26 changes: 20 additions & 6 deletions block/block-backend.c
View file
Expand Up @@ -121,6 +121,10 @@ static QTAILQ_HEAD(, BlockBackend) block_backends =
static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
QTAILQ_HEAD_INITIALIZER(monitor_block_backends);

static int coroutine_mixed_fn GRAPH_RDLOCK
blk_set_perm_locked(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp);

static void blk_root_inherit_options(BdrvChildRole role, bool parent_is_format,
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
Expand Down Expand Up @@ -186,7 +190,7 @@ static void blk_vm_state_changed(void *opaque, bool running, RunState state)
*
* If an error is returned, the VM cannot be allowed to be resumed.
*/
static void blk_root_activate(BdrvChild *child, Error **errp)
static void GRAPH_RDLOCK blk_root_activate(BdrvChild *child, Error **errp)
{
BlockBackend *blk = child->opaque;
Error *local_err = NULL;
Expand All @@ -207,7 +211,7 @@ static void blk_root_activate(BdrvChild *child, Error **errp)
*/
saved_shared_perm = blk->shared_perm;

blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
blk_set_perm_locked(blk, blk->perm, BLK_PERM_ALL, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
Expand All @@ -226,7 +230,7 @@ static void blk_root_activate(BdrvChild *child, Error **errp)
return;
}

blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
blk_set_perm_locked(blk, blk->perm, blk->shared_perm, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
Expand Down Expand Up @@ -259,7 +263,7 @@ static bool blk_can_inactivate(BlockBackend *blk)
return blk->force_allow_inactivate;
}

static int blk_root_inactivate(BdrvChild *child)
static int GRAPH_RDLOCK blk_root_inactivate(BdrvChild *child)
{
BlockBackend *blk = child->opaque;

Expand Down Expand Up @@ -953,8 +957,9 @@ int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp)
/*
* Sets the permission bitmasks that the user of the BlockBackend needs.
*/
int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp)
static int coroutine_mixed_fn GRAPH_RDLOCK
blk_set_perm_locked(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp)
{
int ret;
GLOBAL_STATE_CODE();
Expand All @@ -972,6 +977,15 @@ int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
return 0;
}

int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();

return blk_set_perm_locked(blk, perm, shared_perm, errp);
}

void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
{
GLOBAL_STATE_CODE();
Expand Down
6 changes: 4 additions & 2 deletions block/crypto.c
View file
Expand Up @@ -777,7 +777,7 @@ block_crypto_get_specific_info_luks(BlockDriverState *bs, Error **errp)
return spec_info;
}

static int
static int GRAPH_RDLOCK
block_crypto_amend_prepare(BlockDriverState *bs, Error **errp)
{
BlockCrypto *crypto = bs->opaque;
Expand All @@ -793,7 +793,7 @@ block_crypto_amend_prepare(BlockDriverState *bs, Error **errp)
return ret;
}

static void
static void GRAPH_RDLOCK
block_crypto_amend_cleanup(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
Expand Down Expand Up @@ -841,6 +841,8 @@ block_crypto_amend_options_luks(BlockDriverState *bs,
QCryptoBlockAmendOptions *amend_options = NULL;
int ret = -EINVAL;

assume_graph_lock(); /* FIXME */

assert(crypto);
assert(crypto->block);

Expand Down
8 changes: 8 additions & 0 deletions block/mirror.c
View file
Expand Up @@ -702,8 +702,12 @@ static int mirror_exit_common(Job *job)
* mirror_top_bs from now on, so keep it drained. */
bdrv_drained_begin(mirror_top_bs);
bs_opaque->stop = true;

bdrv_graph_rdlock_main_loop();
bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
&error_abort);
bdrv_graph_rdunlock_main_loop();

if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
BlockDriverState *backing = s->is_none_mode ? src : s->base;
BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs);
Expand Down Expand Up @@ -1670,6 +1674,8 @@ static BlockJob *mirror_start_job(
uint64_t target_perms, target_shared_perms;
int ret;

GLOBAL_STATE_CODE();

if (granularity == 0) {
granularity = bdrv_get_default_bitmap_granularity(target);
}
Expand Down Expand Up @@ -1906,8 +1912,10 @@ static BlockJob *mirror_start_job(
}

bs_opaque->stop = true;
bdrv_graph_rdlock_main_loop();
bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
&error_abort);
bdrv_graph_rdunlock_main_loop();
bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);

bdrv_unref(mirror_top_bs);
Expand Down
2 changes: 2 additions & 0 deletions block/vmdk.c
View file
Expand Up @@ -1309,6 +1309,8 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
BDRVVmdkState *s = bs->opaque;
uint32_t magic;

GRAPH_RDLOCK_GUARD_MAINLOOP();

ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
if (ret < 0) {
return ret;
Expand Down
6 changes: 3 additions & 3 deletions include/block/block_int-common.h
View file
Expand Up @@ -311,7 +311,7 @@ struct BlockDriver {
*/
void (*bdrv_cancel_in_flight)(BlockDriverState *bs);

int (*bdrv_inactivate)(BlockDriverState *bs);
int GRAPH_RDLOCK_PTR (*bdrv_inactivate)(BlockDriverState *bs);

int (*bdrv_snapshot_create)(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info);
Expand Down Expand Up @@ -944,8 +944,8 @@ struct BdrvChildClass {
* when migration is completing) and it can start/stop requesting
* permissions and doing I/O on it.
*/
void (*activate)(BdrvChild *child, Error **errp);
int (*inactivate)(BdrvChild *child);
void GRAPH_RDLOCK_PTR (*activate)(BdrvChild *child, Error **errp);
int GRAPH_RDLOCK_PTR (*inactivate)(BdrvChild *child);

void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child);
void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child);
Expand Down
8 changes: 5 additions & 3 deletions include/block/block_int-global-state.h
View file
Expand Up @@ -212,8 +212,9 @@ void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
* bdrv_child_refresh_perms() instead and make the parent's
* .bdrv_child_perm() implementation return the correct values.
*/
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp);
int GRAPH_RDLOCK
bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp);

/**
* Calls bs->drv->bdrv_child_perm() and updates the child's permission
Expand All @@ -223,7 +224,8 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
* values than before, but which will not result in the block layer
* automatically refreshing the permissions.
*/
int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp);
int GRAPH_RDLOCK
bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp);

bool GRAPH_RDLOCK bdrv_recurse_can_replace(BlockDriverState *bs,
BlockDriverState *to_replace);
Expand Down
4 changes: 2 additions & 2 deletions include/sysemu/block-backend-global-state.h
View file
Expand Up @@ -61,8 +61,8 @@ int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp);
int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp);
bool bdrv_has_blk(BlockDriverState *bs);
bool bdrv_is_root_node(BlockDriverState *bs);
int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
Error **errp);
int GRAPH_UNLOCKED blk_set_perm(BlockBackend *blk, uint64_t perm,
uint64_t shared_perm, Error **errp);
void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm);

void blk_iostatus_enable(BlockBackend *blk);
Expand Down
4 changes: 4 additions & 0 deletions tests/unit/test-bdrv-graph-mod.c
View file
Expand Up @@ -372,6 +372,9 @@ static void test_parallel_perm_update(void)

/* Select fl1 as first child to be active */
s->selected = c_fl1;

bdrv_graph_rdlock_main_loop();

bdrv_child_refresh_perms(top, top->children.lh_first, &error_abort);

assert(c_fl1->perm & BLK_PERM_WRITE);
Expand All @@ -391,6 +394,7 @@ static void test_parallel_perm_update(void)
assert(c_fl1->perm & BLK_PERM_WRITE);
assert(!(c_fl2->perm & BLK_PERM_WRITE));

bdrv_graph_rdunlock_main_loop();
bdrv_unref(top);
}

Expand Down

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