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Subject[PATCH net-next 04/15] ethtool: add ethnl_parse_bitset() helper
Date
Unlike other SET type commands, modifying netdev features is required to
provide a reply telling userspace what was actually changed, compared to
what was requested. For that purpose, the "modified" flag provided by
ethnl_update_bitset() is not sufficient, we need full information which
bits were requested to change.

Therefore provide ethnl_parse_bitset() returning effective value and mask
bitmaps equivalent to the contents of a bitset nested attribute.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
net/ethtool/bitset.c | 94 ++++++++++++++++++++++++++++++++++++++++++++
net/ethtool/bitset.h | 4 ++
2 files changed, 98 insertions(+)

diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
index ef9197541cb3..db2935206f3d 100644
--- a/net/ethtool/bitset.c
+++ b/net/ethtool/bitset.c
@@ -588,6 +588,100 @@ int ethnl_update_bitset32(u32 *bitmap, unsigned int nbits,
return 0;
}

+/**
+ * ethnl_parse_bitset() - Compute effective value and mask from bitset nest
+ * @val: unsigned long based bitmap to put value into
+ * @mask: unsigned long based bitmap to put mask into
+ * @nbits: size of @val and @mask bitmaps
+ * @attr: nest attribute to parse and apply
+ * @names: array of bit names; may be null for compact format
+ * @extack: extack for error reporting
+ *
+ * Provide @nbits size long bitmaps for value and mask so that
+ * x = (val & mask) | (x & ~mask) would modify any @nbits sized bitmap x
+ * the same way ethnl_update_bitset() with the same bitset attribute would.
+ *
+ * Return: negative error code on failure, 0 on success
+ */
+int ethnl_parse_bitset(unsigned long *val, unsigned long *mask,
+ unsigned int nbits, const struct nlattr *attr,
+ ethnl_string_array_t names,
+ struct netlink_ext_ack *extack)
+{
+ struct nlattr *tb[ETHTOOL_A_BITSET_MAX + 1];
+ const struct nlattr *bit_attr;
+ bool no_mask;
+ int rem;
+ int ret;
+
+ if (!attr)
+ return 0;
+ ret = nla_parse_nested(tb, ETHTOOL_A_BITSET_MAX, attr, bitset_policy,
+ extack);
+ if (ret < 0)
+ return ret;
+ no_mask = tb[ETHTOOL_A_BITSET_NOMASK];
+
+ if (!tb[ETHTOOL_A_BITSET_BITS]) {
+ unsigned int change_bits;
+
+ ret = ethnl_compact_sanity_checks(nbits, attr, tb, extack);
+ if (ret < 0)
+ return ret;
+
+ change_bits = nla_get_u32(tb[ETHTOOL_A_BITSET_SIZE]);
+ bitmap_from_arr32(val, nla_data(tb[ETHTOOL_A_BITSET_VALUE]),
+ change_bits);
+ if (change_bits < nbits)
+ bitmap_clear(val, change_bits, nbits - change_bits);
+ if (no_mask) {
+ bitmap_fill(mask, nbits);
+ } else {
+ bitmap_from_arr32(mask,
+ nla_data(tb[ETHTOOL_A_BITSET_MASK]),
+ change_bits);
+ if (change_bits < nbits)
+ bitmap_clear(mask, change_bits,
+ nbits - change_bits);
+ }
+
+ return 0;
+ }
+
+ if (tb[ETHTOOL_A_BITSET_VALUE]) {
+ NL_SET_ERR_MSG_ATTR(extack, tb[ETHTOOL_A_BITSET_VALUE],
+ "value only allowed in compact bitset");
+ return -EINVAL;
+ }
+ if (tb[ETHTOOL_A_BITSET_MASK]) {
+ NL_SET_ERR_MSG_ATTR(extack, tb[ETHTOOL_A_BITSET_MASK],
+ "mask only allowed in compact bitset");
+ return -EINVAL;
+ }
+
+ bitmap_zero(val, nbits);
+ if (no_mask)
+ bitmap_fill(mask, nbits);
+ else
+ bitmap_zero(mask, nbits);
+
+ nla_for_each_nested(bit_attr, tb[ETHTOOL_A_BITSET_BITS], rem) {
+ unsigned int idx;
+ bool bit_val;
+
+ ret = ethnl_parse_bit(&idx, &bit_val, nbits, bit_attr, no_mask,
+ names, extack);
+ if (ret < 0)
+ return ret;
+ if (bit_val)
+ set_bit(idx, val);
+ if (!no_mask)
+ set_bit(idx, mask);
+ }
+
+ return 0;
+}
+
#if BITS_PER_LONG == 64 && defined(__BIG_ENDIAN)

/* 64-bit big endian architectures are the only case when u32 based bitmaps
diff --git a/net/ethtool/bitset.h b/net/ethtool/bitset.h
index b849f9d19676..c2c2e0051d00 100644
--- a/net/ethtool/bitset.h
+++ b/net/ethtool/bitset.h
@@ -26,5 +26,9 @@ int ethnl_update_bitset(unsigned long *bitmap, unsigned int nbits,
int ethnl_update_bitset32(u32 *bitmap, unsigned int nbits,
const struct nlattr *attr, ethnl_string_array_t names,
struct netlink_ext_ack *extack, bool *mod);
+int ethnl_parse_bitset(unsigned long *val, unsigned long *mask,
+ unsigned int nbits, const struct nlattr *attr,
+ ethnl_string_array_t names,
+ struct netlink_ext_ack *extack);

#endif /* _NET_ETHTOOL_BITSET_H */
--
2.25.1
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