net: fill in MODULE_DESCRIPTION()s for net/sched

W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to the network schedulers.

Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20240208164244.3818498-8-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/sched/em_canid.c

@@ -222,6 +222,7 @@ static void __exit exit_em_canid(void)
 	tcf_em_unregister(&em_canid_ops);
 }
 
+MODULE_DESCRIPTION("ematch classifier to match CAN IDs embedded in skb CAN frames");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_canid);

net/sched/em_cmp.c

@@ -87,6 +87,7 @@ static void __exit exit_em_cmp(void)
 	tcf_em_unregister(&em_cmp_ops);
 }
 
+MODULE_DESCRIPTION("ematch classifier for basic data types(8/16/32 bit) against skb data");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_cmp);

net/sched/em_meta.c

@@ -1006,6 +1006,7 @@ static void __exit exit_em_meta(void)
 	tcf_em_unregister(&em_meta_ops);
 }
 
+MODULE_DESCRIPTION("ematch classifier for various internal kernel metadata, skb metadata and sk metadata");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_meta);

net/sched/em_nbyte.c

@@ -68,6 +68,7 @@ static void __exit exit_em_nbyte(void)
 	tcf_em_unregister(&em_nbyte_ops);
 }
 
+MODULE_DESCRIPTION("ematch classifier for arbitrary skb multi-bytes");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_nbyte);

net/sched/em_text.c

@@ -147,6 +147,7 @@ static void __exit exit_em_text(void)
 	tcf_em_unregister(&em_text_ops);
 }
 
+MODULE_DESCRIPTION("ematch classifier for embedded text in skbs");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_text);

net/sched/em_u32.c

@@ -52,6 +52,7 @@ static void __exit exit_em_u32(void)
 	tcf_em_unregister(&em_u32_ops);
 }
 
+MODULE_DESCRIPTION("ematch skb classifier using 32 bit chunks of data");
 MODULE_LICENSE("GPL");
 
 module_init(init_em_u32);