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Re: [PATCH 10/29] drivers, md: convert stripe_head.count from atomic_t to refcount_t

From Shaohua Li <shli@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 10/29] drivers, md: convert stripe_head.count from atomic_t to refcount_t
Date 2017-03-07 20:20 +0100
Message-ID <tisOm-3ze-29@gated-at.bofh.it> (permalink)
References <ti1O9-Yn-3@gated-at.bofh.it> <ti1O9-Yn-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Mar 06, 2017 at 04:20:57PM +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>
> ---
>  drivers/md/raid5-cache.c |  8 +++---
>  drivers/md/raid5.c       | 66 ++++++++++++++++++++++++------------------------
>  drivers/md/raid5.h       |  3 ++-
>  3 files changed, 39 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

snip
>  	       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 +5240,7 @@ 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_inc_not_zero(&sh->count));

This changes the behavior. refcount_inc_not_zero doesn't inc if original value is 0

Thanks,
Shaohua

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[PATCH 00/29] drivers, mics refcount conversions Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
  [PATCH 08/29] drivers, md: convert mddev.active from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
    Re: [PATCH 08/29] drivers, md: convert mddev.active from atomic_t to  refcount_t Shaohua Li <shli@kernel.org> - 2017-03-07 20:20 +0100
      RE: [PATCH 08/29] drivers, md: convert mddev.active from atomic_t  to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-08 10:50 +0100
        Re: [PATCH 08/29] drivers, md: convert mddev.active from atomic_t to  refcount_t "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org> - 2017-03-08 11:30 +0100
  [PATCH 10/29] drivers, md: convert stripe_head.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
    Re: [PATCH 10/29] drivers, md: convert stripe_head.count from  atomic_t to refcount_t Shaohua Li <shli@kernel.org> - 2017-03-07 20:20 +0100
      RE: [PATCH 10/29] drivers, md: convert stripe_head.count from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-08 10:50 +0100
  [PATCH 26/29] drivers, usb: convert dev_data.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
  [PATCH 06/29] drivers, md: convert dm_cache_metadata.ref_count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
  [PATCH 24/29] drivers: convert iblock_req.pending from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
    Re: [PATCH 24/29] drivers: convert iblock_req.pending from atomic_t  to refcount_t "Nicholas A. Bellinger" <nab@linux-iscsi.org> - 2017-03-08 08:50 +0100
  [PATCH 02/29] drivers, firewire: convert fw_node.ref_count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:30 +0100
  [PATCH 13/29] drivers, media: convert vb2_vmarea_handler.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
    Re: [PATCH 13/29] drivers, media: convert  vb2_vmarea_handler.refcount from atomic_t to refcount_t Sakari Ailus <sakari.ailus@iki.fi> - 2017-03-07 10:00 +0100
      RE: [PATCH 13/29] drivers, media: convert  vb2_vmarea_handler.refcount from atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-07 16:00 +0100
  [PATCH 16/29] drivers, media: convert vb2_vmalloc_buf.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 15/29] drivers, media: convert vb2_dma_sg_buf.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
    Re: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from  atomic_t to refcount_t Chris Leech <cleech@redhat.com> - 2017-03-08 19:50 +0100
      RE: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-09 08:30 +0100
        Re: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from  atomic_t to refcount_t Johannes Thumshirn <jthumshirn@suse.de> - 2017-03-09 09:50 +0100
          RE: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-09 10:30 +0100
            Re: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from  atomic_t to refcount_t Johannes Thumshirn <jthumshirn@suse.de> - 2017-03-09 10:40 +0100
  [PATCH 27/29] drivers, usb: convert ep_data.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 19/29] drivers, s390: convert lcs_reply.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
    Re: [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from  atomic_t to refcount_t Johannes Thumshirn <jthumshirn@suse.de> - 2017-03-06 16:30 +0100
      Re: [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from  atomic_t to refcount_t Benjamin Block <bblock@linux.vnet.ibm.com> - 2017-03-06 20:50 +0100
      RE: [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-07 12:20 +0100
      RE: [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-08 15:00 +0100
        Re: [PATCH 21/29] drivers, s390: convert fc_fcp_pkt.ref_cnt from  atomic_t to refcount_t Johannes Thumshirn <jthumshirn@suse.de> - 2017-03-08 16:30 +0100
  [PATCH 23/29] drivers: convert vme_user_vma_priv.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 14/29] drivers, media: convert vb2_dc_buf.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 04/29] drivers, connector: convert cn_callback_entry.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 05/29] drivers, md, bcache: convert cached_dev.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 17/29] drivers, pci: convert hv_pci_dev.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
    Re: [PATCH 17/29] drivers, pci: convert hv_pci_dev.refs from  atomic_t to refcount_t Bjorn Helgaas <helgaas@kernel.org> - 2017-03-06 23:30 +0100
      Re: [PATCH 17/29] drivers, pci: convert hv_pci_dev.refs from  atomic_t to refcount_t Stephen Hemminger <stephen@networkplumber.org> - 2017-03-07 21:00 +0100
  [PATCH 20/29] drivers, s390: convert qeth_reply.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 07/29] drivers, md: convert dm_dev_internal.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 29/29] drivers, xen: convert grant_map.users from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
    Re: [Xen-devel] [PATCH 29/29] drivers, xen: convert grant_map.users  from atomic_t to refcount_t Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-06 19:50 +0100
      RE: [Xen-devel] [PATCH 29/29] drivers, xen: convert grant_map.users  from atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-08 15:10 +0100
        Re: [Xen-devel] [PATCH 29/29] drivers, xen: convert grant_map.users  from atomic_t to refcount_t Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-03-08 18:50 +0100
          RE: [Xen-devel] [PATCH 29/29] drivers, xen: convert grant_map.users  from atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-09 08:30 +0100
  [PATCH 25/29] drivers, usb: convert ffs_data.ref from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 28/29] drivers: convert sbd_duart.map_guard from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:40 +0100
  [PATCH 09/29] drivers, md: convert table_device.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:50 +0100
  [PATCH 01/29] drivers, block: convert xen_blkif.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:50 +0100
  [PATCH 18/29] drivers, s390: convert urdev.ref_count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 15:50 +0100
  [PATCH 03/29] drivers, char: convert vma_data.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-06 16:30 +0100

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