lkml.org 
[lkml]   [2017]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 07/19] net: netlink/netfilter: Kill off ACCESS_ONCE()
    Date
    From: Mark Rutland <mark.rutland@arm.com>

    For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
    preference to ACCESS_ONCE(), and new code is expected to use one of the
    former. So far, there's been no reason to change most existing uses of
    ACCESS_ONCE(), as these aren't currently harmful.

    However, for some features it is necessary to instrument reads and
    writes separately, which is not possible with ACCESS_ONCE(). This
    distinction is critical to correct operation.

    It's possible to transform the bulk of kernel code using the Coccinelle
    script below. However, this doesn't handle comments, leaving references
    to ACCESS_ONCE() instances which have been removed. As a preparatory
    step, this patch converts netlink and netfilter code and comments to use
    {READ,WRITE}_ONCE() consistently.

    ----
    virtual patch

    @ depends on patch @
    expression E1, E2;
    @@

    - ACCESS_ONCE(E1) = E2
    + WRITE_ONCE(E1, E2)

    @ depends on patch @
    expression E;
    @@

    - ACCESS_ONCE(E)
    + READ_ONCE(E)
    ----

    Signed-off-by: Mark Rutland <mark.rutland@arm.com>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Florian Westphal <fw@strlen.de>
    Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
    Cc: Pablo Neira Ayuso <pablo@netfilter.org>
    ---
    include/linux/genetlink.h | 2 +-
    include/linux/netfilter/nfnetlink.h | 2 +-
    include/linux/rtnetlink.h | 2 +-
    include/net/netfilter/nf_tables.h | 4 ++--
    net/netfilter/ipvs/ip_vs_sync.c | 2 +-
    net/netfilter/nfnetlink_queue.c | 4 ++--
    6 files changed, 8 insertions(+), 8 deletions(-)

    diff --git a/include/linux/genetlink.h b/include/linux/genetlink.h
    index a4c61cbce777..0e694cf62414 100644
    --- a/include/linux/genetlink.h
    +++ b/include/linux/genetlink.h
    @@ -30,7 +30,7 @@ extern wait_queue_head_t genl_sk_destructing_waitq;
    * @p: The pointer to read, prior to dereferencing
    *
    * Return the value of the specified RCU-protected pointer, but omit
    - * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because
    + * both the smp_read_barrier_depends() and the READ_ONCE(), because
    * caller holds genl mutex.
    */
    #define genl_dereference(p) \
    diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
    index 41d04e9d088a..0f47a4aa7fc4 100644
    --- a/include/linux/netfilter/nfnetlink.h
    +++ b/include/linux/netfilter/nfnetlink.h
    @@ -66,7 +66,7 @@ static inline bool lockdep_nfnl_is_held(__u8 subsys_id)
    * @ss: The nfnetlink subsystem ID
    *
    * Return the value of the specified RCU-protected pointer, but omit
    - * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because
    + * both the smp_read_barrier_depends() and the READ_ONCE(), because
    * caller holds the NFNL subsystem mutex.
    */
    #define nfnl_dereference(p, ss) \
    diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
    index dea59c8eec54..765f7b915475 100644
    --- a/include/linux/rtnetlink.h
    +++ b/include/linux/rtnetlink.h
    @@ -67,7 +67,7 @@ static inline bool lockdep_rtnl_is_held(void)
    * @p: The pointer to read, prior to dereferencing
    *
    * Return the value of the specified RCU-protected pointer, but omit
    - * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because
    + * both the smp_read_barrier_depends() and the READ_ONCE(), because
    * caller holds RTNL.
    */
    #define rtnl_dereference(p) \
    diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
    index 0f5b12a4ad09..5c68e279eaea 100644
    --- a/include/net/netfilter/nf_tables.h
    +++ b/include/net/netfilter/nf_tables.h
    @@ -1164,8 +1164,8 @@ static inline u8 nft_genmask_next(const struct net *net)

    static inline u8 nft_genmask_cur(const struct net *net)
    {
    - /* Use ACCESS_ONCE() to prevent refetching the value for atomicity */
    - return 1 << ACCESS_ONCE(net->nft.gencursor);
    + /* Use READ_ONCE() to prevent refetching the value for atomicity */
    + return 1 << READ_ONCE(net->nft.gencursor);
    }

    #define NFT_GENMASK_ANY ((1 << 0) | (1 << 1))
    diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
    index 0e5b64a75da0..1cfffd42d1e2 100644
    --- a/net/netfilter/ipvs/ip_vs_sync.c
    +++ b/net/netfilter/ipvs/ip_vs_sync.c
    @@ -457,7 +457,7 @@ static inline bool in_persistence(struct ip_vs_conn *cp)
    static int ip_vs_sync_conn_needed(struct netns_ipvs *ipvs,
    struct ip_vs_conn *cp, int pkts)
    {
    - unsigned long orig = ACCESS_ONCE(cp->sync_endtime);
    + unsigned long orig = READ_ONCE(cp->sync_endtime);
    unsigned long now = jiffies;
    unsigned long n = (now + cp->timeout) & ~3UL;
    unsigned int sync_refresh_period;
    diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
    index c9796629858f..a16356cacec3 100644
    --- a/net/netfilter/nfnetlink_queue.c
    +++ b/net/netfilter/nfnetlink_queue.c
    @@ -401,7 +401,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,

    outdev = entry->state.out;

    - switch ((enum nfqnl_config_mode)ACCESS_ONCE(queue->copy_mode)) {
    + switch ((enum nfqnl_config_mode)READ_ONCE(queue->copy_mode)) {
    case NFQNL_COPY_META:
    case NFQNL_COPY_NONE:
    break;
    @@ -412,7 +412,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
    skb_checksum_help(entskb))
    return NULL;

    - data_len = ACCESS_ONCE(queue->copy_range);
    + data_len = READ_ONCE(queue->copy_range);
    if (data_len > entskb->len)
    data_len = entskb->len;

    --
    2.5.2
    \
     
     \ /
      Last update: 2017-10-23 23:10    [W:4.237 / U:0.788 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site