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Date: Thu, 15 Dec 2022 10:11:03 +0100 From: Jiri Pirko <jiri@...nulli.us> To: Jakub Kicinski <kuba@...nel.org> Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com, jacob.e.keller@...el.com, leon@...nel.org Subject: Re: [RFC net-next 14/15] devlink: add by-instance dump infra Thu, Dec 15, 2022 at 03:01:54AM CET, kuba@...nel.org wrote: >Most dumpit implementations walk the devlink instances. >This requires careful lock taking and reference dropping. >Factor the loop out and provide just a callback to handle >a single instance dump. > >Convert one user as an example, other users converted >in the next change. > >Slightly inspired by ethtool netlink code. > >Signed-off-by: Jakub Kicinski <kuba@...nel.org> >--- > net/devlink/basic.c | 55 ++++++++++++++++--------------------- > net/devlink/devl_internal.h | 10 +++++++ > net/devlink/netlink.c | 33 ++++++++++++++++++++++ > 3 files changed, 67 insertions(+), 31 deletions(-) > >diff --git a/net/devlink/basic.c b/net/devlink/basic.c >index c6ad8133fc23..f18d8dcf9751 100644 >--- a/net/devlink/basic.c >+++ b/net/devlink/basic.c >@@ -1219,47 +1219,40 @@ static void devlink_rate_notify(struct devlink_rate *devlink_rate, > 0, DEVLINK_MCGRP_CONFIG, GFP_KERNEL); > } > >-static int devlink_nl_cmd_rate_get_dumpit(struct sk_buff *msg, >- struct netlink_callback *cb) >+static int >+devlink_nl_cmd_rate_get_dumpinst(struct sk_buff *msg, struct devlink *devlink, >+ struct netlink_callback *cb) > { > struct devlink_nl_dump_state *dump = devl_dump_state(cb); >- struct devlink *devlink; >+ struct devlink_rate *devlink_rate; >+ int idx = 0; > int err = 0; > >- devlink_dump_for_each_instance_get(msg, dump, devlink) { >- struct devlink_rate *devlink_rate; >- int idx = 0; >- >- devl_lock(devlink); >- list_for_each_entry(devlink_rate, &devlink->rate_list, list) { >- enum devlink_command cmd = DEVLINK_CMD_RATE_NEW; >- u32 id = NETLINK_CB(cb->skb).portid; >+ list_for_each_entry(devlink_rate, &devlink->rate_list, list) { >+ enum devlink_command cmd = DEVLINK_CMD_RATE_NEW; >+ u32 id = NETLINK_CB(cb->skb).portid; > >- if (idx < dump->idx) { >- idx++; >- continue; >- } >- err = devlink_nl_rate_fill(msg, devlink_rate, cmd, id, >- cb->nlh->nlmsg_seq, >- NLM_F_MULTI, NULL); >- if (err) { >- devl_unlock(devlink); >- devlink_put(devlink); >- dump->idx = idx; >- goto out; >- } >+ if (idx < dump->idx) { > idx++; >+ continue; > } >- devl_unlock(devlink); >- devlink_put(devlink); >+ err = devlink_nl_rate_fill(msg, devlink_rate, cmd, id, >+ cb->nlh->nlmsg_seq, >+ NLM_F_MULTI, NULL); >+ if (err) { >+ dump->idx = idx; >+ break; >+ } >+ idx++; > } >-out: >- if (err != -EMSGSIZE) >- return err; > >- return msg->len; >+ return err; > } > >+const struct devlink_gen_cmd devl_gen_rate_get = { >+ .dump_one = devlink_nl_cmd_rate_get_dumpinst, >+}; >+ > static int devlink_nl_cmd_rate_get_doit(struct sk_buff *skb, > struct genl_info *info) > { >@@ -9130,7 +9123,7 @@ const struct genl_small_ops devlink_nl_ops[56] = { > { > .cmd = DEVLINK_CMD_RATE_GET, > .doit = devlink_nl_cmd_rate_get_doit, >- .dumpit = devlink_nl_cmd_rate_get_dumpit, >+ .dumpit = devlink_instance_iter_dump, > .internal_flags = DEVLINK_NL_FLAG_NEED_RATE, > /* can be retrieved by unprivileged users */ > }, >diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h >index 5adac38454fd..e49b82dd77cd 100644 >--- a/net/devlink/devl_internal.h >+++ b/net/devlink/devl_internal.h >@@ -122,6 +122,11 @@ struct devlink_nl_dump_state { > }; > }; > >+struct devlink_gen_cmd { >+ int (*dump_one)(struct sk_buff *msg, struct devlink *devlink, >+ struct netlink_callback *cb); >+}; >+ > /* Iterate over devlink pointers which were possible to get reference to. > * devlink_put() needs to be called for each iterated devlink pointer > * in loop body in order to release the reference. >@@ -138,6 +143,9 @@ struct devlink *devlink_get_from_attrs(struct net *net, struct nlattr **attrs); > void devlink_notify_unregister(struct devlink *devlink); > void devlink_notify_register(struct devlink *devlink); > >+int devlink_instance_iter_dump(struct sk_buff *msg, >+ struct netlink_callback *cb); >+ > static inline struct devlink_nl_dump_state * > devl_dump_state(struct netlink_callback *cb) > { >@@ -173,6 +181,8 @@ devlink_linecard_get_from_info(struct devlink *devlink, struct genl_info *info); > void devlink_linecard_put(struct devlink_linecard *linecard); > > /* Rates */ >+extern const struct devlink_gen_cmd devl_gen_rate_get; >+ > struct devlink_rate * > devlink_rate_get_from_info(struct devlink *devlink, struct genl_info *info); > struct devlink_rate * >diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c >index ce1a7d674d14..fcf10c288480 100644 >--- a/net/devlink/netlink.c >+++ b/net/devlink/netlink.c >@@ -5,6 +5,7 @@ > */ > > #include <net/genetlink.h> >+#include <net/sock.h> > > #include "devl_internal.h" > >@@ -177,6 +178,38 @@ static void devlink_nl_post_doit(const struct genl_split_ops *ops, > devlink_put(devlink); > } > >+static const struct devlink_gen_cmd *devl_gen_cmds[] = { >+ [DEVLINK_CMD_RATE_GET] = &devl_gen_rate_get, >+}; Instead of having this extra list of ops struct, woudn't it make sence to rather implement this dumpit_one infra directly as a part of generic netlink code? Something like: { .cmd = DEVLINK_CMD_RATE_GET, .doit = devlink_nl_cmd_rate_get_doit, .dumpit_one = devlink_nl_cmd_rate_get_dumpit_one, .dumpit_one_walk = devlink_nl_dumpit_one_walk, .internal_flags = DEVLINK_NL_FLAG_NEED_RATE, /* can be retrieved by unprivileged users */ }, Where devlink_nl_dumpit_one_walk would be basically your devlink_instance_iter_dump(), it would get an extra arg dumpit_one function pointer from generic netlink code to call per item: int devlink_nl_dumpit_one_walk(struct sk_buff *msg, struct netlink_callback *cb, int (*dumpit_one)(struct sk_buff *msg, struct netlink_callback *cb, void *priv)); { const struct genl_dumpit_info *info = genl_dumpit_info(cb); struct devlink_nl_dump_state *dump = devl_dump_state(cb); struct devlink *devlink; int err = 0; devlink_dump_for_each_instance_get(msg, dump, devlink) { devl_lock(devlink); err = dumpit_one(msg, cb, devlink); devl_unlock(devlink); devlink_put(devlink); if (err) break; /* restart sub-object walk for the next instance */ dump->idx = 0; } if (err != -EMSGSIZE) return err; return msg->len; } Or we can avoid .dumpit_one_walk() and just have classic .dumpit() which would get the dumpit_one() pointer cb->dumpit_one (obtainable by a helper doing a proper check-warn_on on null). >+ >+int devlink_instance_iter_dump(struct sk_buff *msg, struct netlink_callback *cb) >+{ >+ const struct genl_dumpit_info *info = genl_dumpit_info(cb); >+ struct devlink_nl_dump_state *dump = devl_dump_state(cb); >+ const struct devlink_gen_cmd *cmd; >+ struct devlink *devlink; >+ int err = 0; >+ >+ cmd = devl_gen_cmds[info->op.cmd]; >+ >+ devlink_dump_for_each_instance_get(msg, dump, devlink) { >+ devl_lock(devlink); >+ err = cmd->dump_one(msg, devlink, cb); >+ devl_unlock(devlink); >+ devlink_put(devlink); >+ >+ if (err) >+ break; >+ >+ /* restart sub-object walk for the next instance */ >+ dump->idx = 0; >+ } >+ >+ if (err != -EMSGSIZE) >+ return err; >+ return msg->len; >+} >+ > struct genl_family devlink_nl_family __ro_after_init = { > .name = DEVLINK_GENL_NAME, > .version = DEVLINK_GENL_VERSION, >-- >2.38.1 >
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