]> git.ipfire.org Git - thirdparty/linux.git/commitdiff
can: raw: use bitfields to store flags in struct raw_sock
authorVincent Mailhol <mailhol@kernel.org>
Wed, 17 Sep 2025 04:48:25 +0000 (13:48 +0900)
committerMarc Kleine-Budde <mkl@pengutronix.de>
Fri, 19 Sep 2025 18:56:34 +0000 (20:56 +0200)
The bound, loopback, recv_own_msgs, fd_frames, xl_frames and
join_filters fields of struct raw_sock just need to store one bit of
information.

Declare all those members as a bitfields of type unsigned int and
width one bit.

Add a temporary variable to raw_setsockopt() and raw_getsockopt() to
make the conversion between the stored bits and the socket interface.

This reduces the size of struct raw_sock by sixteen bytes.

Statistics before:

  $ pahole --class_name=raw_sock net/can/raw.o
  struct raw_sock {
   struct sock                sk __attribute__((__aligned__(8))); /*     0   776 */

   /* XXX last struct has 1 bit hole */

   /* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */
   int                        bound;                /*   776     4 */
   int                        ifindex;              /*   780     4 */
   struct net_device *        dev;                  /*   784     8 */
   netdevice_tracker          dev_tracker;          /*   792     0 */
   struct list_head           notifier;             /*   792    16 */
   int                        loopback;             /*   808     4 */
   int                        recv_own_msgs;        /*   812     4 */
   int                        fd_frames;            /*   816     4 */
   int                        xl_frames;            /*   820     4 */
   struct can_raw_vcid_options raw_vcid_opts;       /*   824     4 */
   canid_t                    tx_vcid_shifted;      /*   828     4 */
   /* --- cacheline 13 boundary (832 bytes) --- */
   canid_t                    rx_vcid_shifted;      /*   832     4 */
   canid_t                    rx_vcid_mask_shifted; /*   836     4 */
   int                        join_filters;         /*   840     4 */
   int                        count;                /*   844     4 */
   struct can_filter          dfilter;              /*   848     8 */
   struct can_filter *        filter;               /*   856     8 */
   can_err_mask_t             err_mask;             /*   864     4 */

   /* XXX 4 bytes hole, try to pack */

   struct uniqframe *         uniq;                 /*   872     8 */

   /* size: 880, cachelines: 14, members: 20 */
   /* sum members: 876, holes: 1, sum holes: 4 */
   /* member types with bit holes: 1, total: 1 */
   /* forced alignments: 1 */
   /* last cacheline: 48 bytes */
  } __attribute__((__aligned__(8)));

...and after:

  $ pahole --class_name=raw_sock net/can/raw.o
  struct raw_sock {
   struct sock                sk __attribute__((__aligned__(8))); /*     0   776 */

   /* XXX last struct has 1 bit hole */

   /* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */
   int                        ifindex;              /*   776     4 */

   /* XXX 4 bytes hole, try to pack */

   struct net_device *        dev;                  /*   784     8 */
   netdevice_tracker          dev_tracker;          /*   792     0 */
   struct list_head           notifier;             /*   792    16 */
   unsigned int               bound:1;              /*   808: 0  4 */
   unsigned int               loopback:1;           /*   808: 1  4 */
   unsigned int               recv_own_msgs:1;      /*   808: 2  4 */
   unsigned int               fd_frames:1;          /*   808: 3  4 */
   unsigned int               xl_frames:1;          /*   808: 4  4 */
   unsigned int               join_filters:1;       /*   808: 5  4 */

   /* XXX 2 bits hole, try to pack */
   /* Bitfield combined with next fields */

   struct can_raw_vcid_options raw_vcid_opts;       /*   809     4 */

   /* XXX 3 bytes hole, try to pack */

   canid_t                    tx_vcid_shifted;      /*   816     4 */
   canid_t                    rx_vcid_shifted;      /*   820     4 */
   canid_t                    rx_vcid_mask_shifted; /*   824     4 */
   int                        count;                /*   828     4 */
   /* --- cacheline 13 boundary (832 bytes) --- */
   struct can_filter          dfilter;              /*   832     8 */
   struct can_filter *        filter;               /*   840     8 */
   can_err_mask_t             err_mask;             /*   848     4 */

   /* XXX 4 bytes hole, try to pack */

   struct uniqframe *         uniq;                 /*   856     8 */

   /* size: 864, cachelines: 14, members: 20 */
   /* sum members: 852, holes: 3, sum holes: 11 */
   /* sum bitfield members: 6 bits, bit holes: 1, sum bit holes: 2 bits */
   /* member types with bit holes: 1, total: 1 */
   /* forced alignments: 1 */
   /* last cacheline: 32 bytes */
  } __attribute__((__aligned__(8)));

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20250917-can-raw-repack-v2-2-395e8b3a4437@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
net/can/raw.c

index db21d8a8c54d1b6a25a72c7a9d11d5c94f3187b5..5a5ded519cd1768456c234c42dc4e865f7350dab 100644 (file)
@@ -82,20 +82,20 @@ struct uniqframe {
 
 struct raw_sock {
        struct sock sk;
-       int bound;
        int ifindex;
        struct net_device *dev;
        netdevice_tracker dev_tracker;
        struct list_head notifier;
-       int loopback;
-       int recv_own_msgs;
-       int fd_frames;
-       int xl_frames;
+       unsigned int bound:1;
+       unsigned int loopback:1;
+       unsigned int recv_own_msgs:1;
+       unsigned int fd_frames:1;
+       unsigned int xl_frames:1;
+       unsigned int join_filters:1;
        struct can_raw_vcid_options raw_vcid_opts;
        canid_t tx_vcid_shifted;
        canid_t rx_vcid_shifted;
        canid_t rx_vcid_mask_shifted;
-       int join_filters;
        int count;                 /* number of active filters */
        struct can_filter dfilter; /* default/single filter */
        struct can_filter *filter; /* pointer to filter(s) */
@@ -560,8 +560,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
        struct can_filter sfilter;         /* single filter */
        struct net_device *dev = NULL;
        can_err_mask_t err_mask = 0;
-       int fd_frames;
        int count = 0;
+       int flag;
        int err = 0;
 
        if (level != SOL_CAN_RAW)
@@ -682,44 +682,48 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                break;
 
        case CAN_RAW_LOOPBACK:
-               if (optlen != sizeof(ro->loopback))
+               if (optlen != sizeof(flag))
                        return -EINVAL;
 
-               if (copy_from_sockptr(&ro->loopback, optval, optlen))
+               if (copy_from_sockptr(&flag, optval, optlen))
                        return -EFAULT;
 
+               ro->loopback = !!flag;
                break;
 
        case CAN_RAW_RECV_OWN_MSGS:
-               if (optlen != sizeof(ro->recv_own_msgs))
+               if (optlen != sizeof(flag))
                        return -EINVAL;
 
-               if (copy_from_sockptr(&ro->recv_own_msgs, optval, optlen))
+               if (copy_from_sockptr(&flag, optval, optlen))
                        return -EFAULT;
 
+               ro->recv_own_msgs = !!flag;
                break;
 
        case CAN_RAW_FD_FRAMES:
-               if (optlen != sizeof(fd_frames))
+               if (optlen != sizeof(flag))
                        return -EINVAL;
 
-               if (copy_from_sockptr(&fd_frames, optval, optlen))
+               if (copy_from_sockptr(&flag, optval, optlen))
                        return -EFAULT;
 
                /* Enabling CAN XL includes CAN FD */
-               if (ro->xl_frames && !fd_frames)
+               if (ro->xl_frames && !flag)
                        return -EINVAL;
 
-               ro->fd_frames = fd_frames;
+               ro->fd_frames = !!flag;
                break;
 
        case CAN_RAW_XL_FRAMES:
-               if (optlen != sizeof(ro->xl_frames))
+               if (optlen != sizeof(flag))
                        return -EINVAL;
 
-               if (copy_from_sockptr(&ro->xl_frames, optval, optlen))
+               if (copy_from_sockptr(&flag, optval, optlen))
                        return -EFAULT;
 
+               ro->xl_frames = !!flag;
+
                /* Enabling CAN XL includes CAN FD */
                if (ro->xl_frames)
                        ro->fd_frames = ro->xl_frames;
@@ -739,12 +743,13 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
                break;
 
        case CAN_RAW_JOIN_FILTERS:
-               if (optlen != sizeof(ro->join_filters))
+               if (optlen != sizeof(flag))
                        return -EINVAL;
 
-               if (copy_from_sockptr(&ro->join_filters, optval, optlen))
+               if (copy_from_sockptr(&flag, optval, optlen))
                        return -EFAULT;
 
+               ro->join_filters = !!flag;
                break;
 
        default:
@@ -758,6 +763,7 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 {
        struct sock *sk = sock->sk;
        struct raw_sock *ro = raw_sk(sk);
+       int flag;
        int len;
        void *val;
 
@@ -806,25 +812,29 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
        case CAN_RAW_LOOPBACK:
                if (len > sizeof(int))
                        len = sizeof(int);
-               val = &ro->loopback;
+               flag = ro->loopback;
+               val = &flag;
                break;
 
        case CAN_RAW_RECV_OWN_MSGS:
                if (len > sizeof(int))
                        len = sizeof(int);
-               val = &ro->recv_own_msgs;
+               flag = ro->recv_own_msgs;
+               val = &flag;
                break;
 
        case CAN_RAW_FD_FRAMES:
                if (len > sizeof(int))
                        len = sizeof(int);
-               val = &ro->fd_frames;
+               flag = ro->fd_frames;
+               val = &flag;
                break;
 
        case CAN_RAW_XL_FRAMES:
                if (len > sizeof(int))
                        len = sizeof(int);
-               val = &ro->xl_frames;
+               flag = ro->xl_frames;
+               val = &flag;
                break;
 
        case CAN_RAW_XL_VCID_OPTS: {
@@ -849,7 +859,8 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
        case CAN_RAW_JOIN_FILTERS:
                if (len > sizeof(int))
                        len = sizeof(int);
-               val = &ro->join_filters;
+               flag = ro->join_filters;
+               val = &flag;
                break;
 
        default: