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    SubjectRe: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from atomic_t to refcount_t
    On Mon, Mar 06, 2017 at 04:21:09PM +0200, Elena Reshetova wrote:
    > 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@intel.com>
    > Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
    > Signed-off-by: Kees Cook <keescook@chromium.org>
    > Signed-off-by: David Windsor <dwindsor@gmail.com>

    This looks OK to me.

    Acked-by: Chris Leech <cleech@redhat.com>

    > ---
    > drivers/scsi/libiscsi.c | 8 ++++----
    > drivers/scsi/qedi/qedi_iscsi.c | 2 +-
    > include/scsi/libiscsi.h | 3 ++-
    > 3 files changed, 7 insertions(+), 6 deletions(-)
    >
    > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
    > index 834d121..7eb1d2c 100644
    > --- a/drivers/scsi/libiscsi.c
    > +++ b/drivers/scsi/libiscsi.c
    > @@ -516,13 +516,13 @@ static void iscsi_free_task(struct iscsi_task *task)
    >
    > void __iscsi_get_task(struct iscsi_task *task)
    > {
    > - atomic_inc(&task->refcount);
    > + refcount_inc(&task->refcount);
    > }
    > EXPORT_SYMBOL_GPL(__iscsi_get_task);
    >
    > void __iscsi_put_task(struct iscsi_task *task)
    > {
    > - if (atomic_dec_and_test(&task->refcount))
    > + if (refcount_dec_and_test(&task->refcount))
    > iscsi_free_task(task);
    > }
    > EXPORT_SYMBOL_GPL(__iscsi_put_task);
    > @@ -744,7 +744,7 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
    > * released by the lld when it has transmitted the task for
    > * pdus we do not expect a response for.
    > */
    > - atomic_set(&task->refcount, 1);
    > + refcount_set(&task->refcount, 1);
    > task->conn = conn;
    > task->sc = NULL;
    > INIT_LIST_HEAD(&task->running);
    > @@ -1616,7 +1616,7 @@ static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn,
    > sc->SCp.phase = conn->session->age;
    > sc->SCp.ptr = (char *) task;
    >
    > - atomic_set(&task->refcount, 1);
    > + refcount_set(&task->refcount, 1);
    > task->state = ISCSI_TASK_PENDING;
    > task->conn = conn;
    > task->sc = sc;
    > diff --git a/drivers/scsi/qedi/qedi_iscsi.c b/drivers/scsi/qedi/qedi_iscsi.c
    > index b9f79d3..3895bd5 100644
    > --- a/drivers/scsi/qedi/qedi_iscsi.c
    > +++ b/drivers/scsi/qedi/qedi_iscsi.c
    > @@ -1372,7 +1372,7 @@ static void qedi_cleanup_task(struct iscsi_task *task)
    > {
    > if (!task->sc || task->state == ISCSI_TASK_PENDING) {
    > QEDI_INFO(NULL, QEDI_LOG_IO, "Returning ref_cnt=%d\n",
    > - atomic_read(&task->refcount));
    > + refcount_read(&task->refcount));
    > return;
    > }
    >
    > diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
    > index b0e275d..24d74b5 100644
    > --- a/include/scsi/libiscsi.h
    > +++ b/include/scsi/libiscsi.h
    > @@ -29,6 +29,7 @@
    > #include <linux/timer.h>
    > #include <linux/workqueue.h>
    > #include <linux/kfifo.h>
    > +#include <linux/refcount.h>
    > #include <scsi/iscsi_proto.h>
    > #include <scsi/iscsi_if.h>
    > #include <scsi/scsi_transport_iscsi.h>
    > @@ -139,7 +140,7 @@ struct iscsi_task {
    >
    > /* state set/tested under session->lock */
    > int state;
    > - atomic_t refcount;
    > + refcount_t refcount;
    > struct list_head running; /* running cmd list */
    > void *dd_data; /* driver/transport data */
    > };
    > --
    > 2.7.4
    >

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