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Date: Thu, 20 Apr 2017 09:37:31 -0700
From: Shaohua Li <shli@...nel.org>
To: "Reshetova, Elena" <elena.reshetova@...el.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
Hans Liljestrand <ishkamiel@...il.com>,
Kees Cook <keescook@...omium.org>,
David Windsor <dwindsor@...il.com>
Subject: Re: [PATCH] drivers, md: convert stripe_head.count from atomic_t to
refcount_t
On Thu, Apr 20, 2017 at 09:15:00AM +0000, Reshetova, Elena wrote:
> Just a ping on this updated patch. Did you find any new issues or could you please apply it?
sorry, for the dalay. I'm in vacation. Since the stripe_head.count could be 0
(and it's not freed), I assume it should stay as atomic_t.
Thanks,
Shaohua
> Best Regards,
> Elena.
>
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> >
> > Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> > Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > Signed-off-by: David Windsor <dwindsor@...il.com>
> > ---
> > drivers/md/raid5-cache.c | 8 +++---
> > drivers/md/raid5.c | 68 +++++++++++++++++++++++++-----------------------
> > drivers/md/raid5.h | 3 ++-
> > 3 files changed, 41 insertions(+), 38 deletions(-)
> >
> > diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> > index 3f307be..6c05e12 100644
> > --- a/drivers/md/raid5-cache.c
> > +++ b/drivers/md/raid5-cache.c
> > @@ -979,7 +979,7 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head
> > *sh)
> > * don't delay.
> > */
> > clear_bit(STRIPE_DELAYED, &sh->state);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > mutex_lock(&log->io_mutex);
> > /* meta + data */
> > @@ -1321,7 +1321,7 @@ static void r5c_flush_stripe(struct r5conf *conf, struct
> > stripe_head *sh)
> > assert_spin_locked(&conf->device_lock);
> >
> > list_del_init(&sh->lru);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > set_bit(STRIPE_HANDLE, &sh->state);
> > atomic_inc(&conf->active_stripes);
> > @@ -1424,7 +1424,7 @@ static void r5c_do_reclaim(struct r5conf *conf)
> > */
> > if (!list_empty(&sh->lru) &&
> > !test_bit(STRIPE_HANDLE, &sh-
> > >state) &&
> > - atomic_read(&sh->count) == 0) {
> > + refcount_read(&sh->count) == 0) {
> > r5c_flush_stripe(conf,
> > sh);
> > if (count++ >=
> > R5C_RECLAIM_STRIPE_GROUP)
> > break;
> > @@ -2650,7 +2650,7 @@ r5c_cache_data(struct r5l_log *log, struct stripe_head
> > *sh,
> > * don't delay.
> > */
> > clear_bit(STRIPE_DELAYED, &sh->state);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > mutex_lock(&log->io_mutex);
> > /* meta + data */
> > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> > index 2ce23b0..7e3913a 100644
> > --- a/drivers/md/raid5.c
> > +++ b/drivers/md/raid5.c
> > @@ -296,7 +296,7 @@ static void do_release_stripe(struct r5conf *conf, struct
> > stripe_head *sh,
> > static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
> > struct list_head
> > *temp_inactive_list)
> > {
> > - if (atomic_dec_and_test(&sh->count))
> > + if (refcount_dec_and_test(&sh->count))
> > do_release_stripe(conf, sh, temp_inactive_list);
> > }
> >
> > @@ -388,7 +388,7 @@ void raid5_release_stripe(struct stripe_head *sh)
> >
> > /* Avoid release_list until the last reference.
> > */
> > - if (atomic_add_unless(&sh->count, -1, 1))
> > + if (refcount_dec_not_one(&sh->count))
> > return;
> >
> > if (unlikely(!conf->mddev->thread) ||
> > @@ -401,7 +401,7 @@ void raid5_release_stripe(struct stripe_head *sh)
> > slow_path:
> > local_irq_save(flags);
> > /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
> > - if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
> > + if (refcount_dec_and_lock(&sh->count, &conf->device_lock)) {
> > INIT_LIST_HEAD(&list);
> > hash = sh->hash_lock_index;
> > do_release_stripe(conf, sh, &list);
> > @@ -491,7 +491,7 @@ static void init_stripe(struct stripe_head *sh, sector_t
> > sector, int previous)
> > struct r5conf *conf = sh->raid_conf;
> > int i, seq;
> >
> > - BUG_ON(atomic_read(&sh->count) != 0);
> > + BUG_ON(refcount_read(&sh->count) != 0);
> > BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
> > BUG_ON(stripe_operations_active(sh));
> > BUG_ON(sh->batch_head);
> > @@ -668,11 +668,11 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t
> > sector,
> > &conf-
> > >cache_state);
> > } else {
> > init_stripe(sh, sector,
> > previous);
> > - atomic_inc(&sh-
> > >count);
> > + refcount_inc(&sh-
> > >count);
> > }
> > - } else if (!atomic_inc_not_zero(&sh->count)) {
> > + } else if (!refcount_inc_not_zero(&sh->count)) {
> > spin_lock(&conf->device_lock);
> > - if (!atomic_read(&sh->count)) {
> > + if (!refcount_read(&sh->count)) {
> > if
> > (!test_bit(STRIPE_HANDLE, &sh->state))
> >
> > atomic_inc(&conf->active_stripes);
> >
> > BUG_ON(list_empty(&sh->lru) &&
> > @@ -688,7 +688,7 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t
> > sector,
> > sh-
> > >group = NULL;
> > }
> > }
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > spin_unlock(&conf->device_lock);
> > }
> > } while (sh == NULL);
> > @@ -752,9 +752,9 @@ static void stripe_add_to_batch_list(struct r5conf *conf,
> > struct stripe_head *sh
> > hash = stripe_hash_locks_hash(head_sector);
> > spin_lock_irq(conf->hash_locks + hash);
> > head = __find_stripe(conf, head_sector, conf->generation);
> > - if (head && !atomic_inc_not_zero(&head->count)) {
> > + if (head && !refcount_inc_not_zero(&head->count)) {
> > spin_lock(&conf->device_lock);
> > - if (!atomic_read(&head->count)) {
> > + if (!refcount_read(&head->count)) {
> > if (!test_bit(STRIPE_HANDLE, &head-
> > >state))
> > atomic_inc(&conf-
> > >active_stripes);
> > BUG_ON(list_empty(&head->lru) &&
> > @@ -770,7 +770,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf,
> > struct stripe_head *sh
> > head->group = NULL;
> > }
> > }
> > - atomic_inc(&head->count);
> > + refcount_inc(&head->count);
> > spin_unlock(&conf->device_lock);
> > }
> > spin_unlock_irq(conf->hash_locks + hash);
> > @@ -833,7 +833,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf,
> > struct stripe_head *sh
> > sh->batch_head->bm_seq = seq;
> > }
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > unlock_out:
> > unlock_two_stripes(head, sh);
> > out:
> > @@ -1036,9 +1036,9 @@ static void ops_run_io(struct stripe_head *sh, struct
> > stripe_head_state *s)
> > pr_debug("%s: for %llu schedule op
> > %d on disc %d\n",
> > __func__, (unsigned
> > long long)sh->sector,
> > bi->bi_opf, i);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > if (sh != head_sh)
> > - atomic_inc(&head_sh-
> > >count);
> > +
> > refcount_inc(&head_sh->count);
> > if (use_new_offset(conf, sh))
> > bi->bi_iter.bi_sector =
> > (sh->sector
> >
> > + rdev->new_data_offset);
> > @@ -1097,9 +1097,9 @@ static void ops_run_io(struct stripe_head *sh, struct
> > stripe_head_state *s)
> > "replacement disc
> > %d\n",
> > __func__, (unsigned
> > long long)sh->sector,
> > rbi->bi_opf, i);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > if (sh != head_sh)
> > - atomic_inc(&head_sh-
> > >count);
> > +
> > refcount_inc(&head_sh->count);
> > if (use_new_offset(conf, sh))
> > rbi->bi_iter.bi_sector =
> > (sh->sector
> >
> > + rrdev->new_data_offset);
> > @@ -1275,7 +1275,7 @@ static void ops_run_biofill(struct stripe_head *sh)
> > }
> > }
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > init_async_submit(&submit, ASYNC_TX_ACK, tx,
> > ops_complete_biofill, sh, NULL);
> > async_trigger_callback(&submit);
> > }
> > @@ -1353,7 +1353,7 @@ ops_run_compute5(struct stripe_head *sh, struct
> > raid5_percpu *percpu)
> > if (i != target)
> > xor_srcs[count++] = sh->dev[i].page;
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > init_async_submit(&submit,
> > ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
> > ops_complete_compute, sh,
> > to_addr_conv(sh, percpu, 0));
> > @@ -1441,7 +1441,7 @@ ops_run_compute6_1(struct stripe_head *sh, struct
> > raid5_percpu *percpu)
> > BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
> > dest = tgt->page;
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > if (target == qd_idx) {
> > count = set_syndrome_sources(blocks, sh,
> > SYNDROME_SRC_ALL);
> > @@ -1516,7 +1516,7 @@ ops_run_compute6_2(struct stripe_head *sh, struct
> > raid5_percpu *percpu)
> > pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
> > __func__, (unsigned long long)sh->sector, faila,
> > failb);
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> >
> > if (failb == syndrome_disks+1) {
> > /* Q disk is one of the missing disks */
> > @@ -1784,7 +1784,7 @@ ops_run_reconstruct5(struct stripe_head *sh, struct
> > raid5_percpu *percpu,
> > break;
> > }
> > if (i >= sh->disks) {
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > set_bit(R5_Discard, &sh->dev[pd_idx].flags);
> > ops_complete_reconstruct(sh);
> > return;
> > @@ -1825,7 +1825,7 @@ ops_run_reconstruct5(struct stripe_head *sh, struct
> > raid5_percpu *percpu,
> > flags = ASYNC_TX_ACK |
> > (prexor ? ASYNC_TX_XOR_DROP_DST
> > : ASYNC_TX_XOR_ZERO_DST);
> >
> > - atomic_inc(&head_sh->count);
> > + refcount_inc(&head_sh->count);
> > init_async_submit(&submit, flags, tx,
> > ops_complete_reconstruct, head_sh,
> > to_addr_conv(sh,
> > percpu, j));
> > } else {
> > @@ -1867,7 +1867,7 @@ ops_run_reconstruct6(struct stripe_head *sh, struct
> > raid5_percpu *percpu,
> > break;
> > }
> > if (i >= sh->disks) {
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
> > set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
> > ops_complete_reconstruct(sh);
> > @@ -1891,7 +1891,7 @@ ops_run_reconstruct6(struct stripe_head *sh, struct
> > raid5_percpu *percpu,
> > struct stripe_head,
> > batch_list) == head_sh;
> >
> > if (last_stripe) {
> > - atomic_inc(&head_sh->count);
> > + refcount_inc(&head_sh->count);
> > init_async_submit(&submit, txflags, tx,
> > ops_complete_reconstruct,
> > head_sh,
> > to_addr_conv(sh, percpu, j));
> > } else
> > @@ -1948,7 +1948,7 @@ static void ops_run_check_p(struct stripe_head *sh,
> > struct raid5_percpu *percpu)
> > tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
> > &sh->ops.zero_sum_result,
> > &submit);
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > init_async_submit(&submit, ASYNC_TX_ACK, tx,
> > ops_complete_check, sh, NULL);
> > tx = async_trigger_callback(&submit);
> > }
> > @@ -1967,7 +1967,7 @@ static void ops_run_check_pq(struct stripe_head *sh,
> > struct raid5_percpu *percpu
> > if (!checkp)
> > srcs[count] = NULL;
> >
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > init_async_submit(&submit, ASYNC_TX_ACK, NULL,
> > ops_complete_check,
> > sh, to_addr_conv(sh, percpu, 0));
> > async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
> > @@ -2057,7 +2057,7 @@ static struct stripe_head *alloc_stripe(struct
> > kmem_cache *sc, gfp_t gfp,
> > INIT_LIST_HEAD(&sh->lru);
> > INIT_LIST_HEAD(&sh->r5c);
> > INIT_LIST_HEAD(&sh->log_list);
> > - atomic_set(&sh->count, 1);
> > + refcount_set(&sh->count, 1);
> > sh->log_start = MaxSector;
> > for (i = 0; i < disks; i++) {
> > struct r5dev *dev = &sh->dev[i];
> > @@ -2354,7 +2354,7 @@ static int drop_one_stripe(struct r5conf *conf)
> > spin_unlock_irq(conf->hash_locks + hash);
> > if (!sh)
> > return 0;
> > - BUG_ON(atomic_read(&sh->count));
> > + BUG_ON(refcount_read(&sh->count));
> > shrink_buffers(sh);
> > kmem_cache_free(conf->slab_cache, sh);
> > atomic_dec(&conf->active_stripes);
> > @@ -2386,7 +2386,7 @@ static void raid5_end_read_request(struct bio * bi)
> > break;
> >
> > pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
> > - (unsigned long long)sh->sector, i, atomic_read(&sh-
> > >count),
> > + (unsigned long long)sh->sector, i,
> > refcount_read(&sh->count),
> > bi->bi_error);
> > if (i == disks) {
> > bio_reset(bi);
> > @@ -2523,7 +2523,7 @@ static void raid5_end_write_request(struct bio *bi)
> > }
> > }
> > pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
> > - (unsigned long long)sh->sector, i, atomic_read(&sh-
> > >count),
> > + (unsigned long long)sh->sector, i,
> > refcount_read(&sh->count),
> > bi->bi_error);
> > if (i == disks) {
> > bio_reset(bi);
> > @@ -4545,7 +4545,7 @@ static void handle_stripe(struct stripe_head *sh)
> > pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
> > "pd_idx=%d, qd_idx=%d\n, check:%d,
> > reconstruct:%d\n",
> > (unsigned long long)sh->sector, sh->state,
> > - atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
> > + refcount_read(&sh->count), sh->pd_idx, sh->qd_idx,
> > sh->check_state, sh->reconstruct_state);
> >
> > analyse_stripe(sh, &s);
> > @@ -4924,7 +4924,7 @@ static void activate_bit_delay(struct r5conf *conf,
> > struct stripe_head *sh = list_entry(head.next, struct
> > stripe_head, lru);
> > int hash;
> > list_del_init(&sh->lru);
> > - atomic_inc(&sh->count);
> > + refcount_inc(&sh->count);
> > hash = sh->hash_lock_index;
> > __release_stripe(conf, sh,
> > &temp_inactive_list[hash]);
> > }
> > @@ -5240,7 +5240,9 @@ static struct stripe_head *__get_priority_stripe(struct
> > r5conf *conf, int group)
> > sh->group = NULL;
> > }
> > list_del_init(&sh->lru);
> > - BUG_ON(atomic_inc_return(&sh->count) != 1);
> > + BUG_ON(refcount_read(&sh->count) != 0);
> > + refcount_set(&sh->count, 1);
> > +
> > return sh;
> > }
> >
> > diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> > index 4bb27b9..a1ed351 100644
> > --- a/drivers/md/raid5.h
> > +++ b/drivers/md/raid5.h
> > @@ -3,6 +3,7 @@
> >
> > #include <linux/raid/xor.h>
> > #include <linux/dmaengine.h>
> > +#include <linux/refcount.h>
> >
> > /*
> > *
> > @@ -207,7 +208,7 @@ struct stripe_head {
> > short ddf_layout;/* use DDF
> > ordering to calculate Q */
> > short hash_lock_index;
> > unsigned long state; /* state
> > flags */
> > - atomic_t count; /* nr of active
> > thread/requests */
> > + refcount_t count; /* nr of active
> > thread/requests */
> > int bm_seq; /*
> > sequence number for bitmap flushes */
> > int disks;
> > /* disks in stripe */
> > int overwrite_disks; /*
> > total overwrite disks in stripe,
> > --
> > 2.7.4
>
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