Differences

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--- net_ioctl [2018/09/03 16:01] – [Sample userspace call] rpjday
+++ net_ioctl [2018/09/04 10:31] (current) – [send_ioctl()] rpjday
@@ Line 18: / Line 18: @@
       * [[https://github.com/torvalds/linux/blob/master/net/core/dev_ioctl.c|dev_ioctl.c]]
-===== Sample userspace call =====
+===== Sample userspace call: ethtool =====
+Git repo is [[https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/|here]].
 ==== send_ioctl() ====
-From ''ethtool'', whicFrom ''ethtool.c'':
+From ''ethtool.c'', a simple wrapper around the ''ioctl()'' call:
 <code>
@@ Line 28: / Line 30: @@
 int send_ioctl(struct cmd_context *ctx, void *cmd)
 {
-        ctx->ifr.ifr_data = cmd;
+        ctx->ifr.ifr_data = cmd;        // command-specific structure
         return ioctl(ctx->fd, SIOCETHTOOL, &ctx->ifr);
 }
 #endif
 </code>
+QUESTION: What is returned in ifreq%%->%%cmd?
 ==== struct cmd_context ====
+From ''internal.h'', ''struct cmd_context'' showing the embedded ''struct ifreq'':
 <code>
@@ Line 48: / Line 54: @@
 </code>
-===== struct ifreq =====
+==== struct ifreq ====
-From ''include/uapi/linux/if.h'':
+From ''include/uapi/linux/if.h'', the unsigned long arg passed with ''ioctl()'':
 <code>
@@ Line 128: / Line 134: @@
 ==== sock_ioctl() ====
-Also from ''net/socket.c'':
+Also from ''net/socket.c'' -- anything related to ''SIOCDEVPRIVATE'' is seriously deprecated (see [[https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/sockios.h#L135|here]]):
 <code>
@@ Line 152: / Line 158: @@
                                 return -EFAULT;
         } else
+</code>
+This reflects wireless extensions, which should not be relevant:
+<code>
 #ifdef CONFIG_WEXT_CORE
         if (cmd >= SIOCIWFIRST && cmd <= SIOCIWLAST) {
@@ Line 157: / Line 168: @@
         } else
 #endif
+</code>
+Finally, this is where we should end up:
+<code>
                 switch (cmd) {
                 case FIOSETOWN: