Re: df2b419a4105 - main - ifnet: add if_foreach_sleep() to allow ifnet iterations with sleep.

Hi Alexander,

Knowing ~nothing about ifnet, if I were to see 'if_foreach_sleep()', my first thought would be that the loop itself was sleeping between each iteration, not that the callback was allowed to sleep. Perhaps this should be renamed to 'if_foreach_sleepable()'?

Just a thought.

Thanks,

Ravi (rpokala@)

-----Original Message-----
From: <owner-src-committers@freebsd.org <mailto:owner-src-committers@freebsd.org>> on behalf of "Alexander V. Chernikov" <melifaro@FreeBSD.org <mailto:melifaro@FreeBSD.org>>
Date: 2023-03-06, Monday at 07:08
To: <src-committers@FreeBSD.org <mailto:src-committers@FreeBSD.org>>, <dev-commits-src-all@FreeBSD.org <mailto:dev-commits-src-all@FreeBSD.org>>, <dev-commits-src-main@FreeBSD.org <mailto:dev-commits-src-main@FreeBSD.org>>
Subject: git: df2b419a4105 - main - ifnet: add if_foreach_sleep() to allow ifnet iterations with sleep.


The branch main has been updated by melifaro:


URL: https://cgit.FreeBSD.org/src/commit/?id=df2b419a4105588384a89a57442ed6c6ca002455 <https://cgit.FreeBSD.org/src/commit/?id=df2b419a4105588384a89a57442ed6c6ca002455>


commit df2b419a4105588384a89a57442ed6c6ca002455
Author: Alexander V. Chernikov <melifaro@FreeBSD.org <mailto:melifaro@FreeBSD.org>>
AuthorDate: 2023-03-04 10:09:09 +0000
Commit: Alexander V. Chernikov <melifaro@FreeBSD.org <mailto:melifaro@FreeBSD.org>>
CommitDate: 2023-03-06 15:08:08 +0000


ifnet: add if_foreach_sleep() to allow ifnet iterations with sleep.


Subscribers: imp, ae, glebius


Differential Revision: https://reviews.freebsd.org/D38904 <https://reviews.freebsd.org/D38904>
---
sys/net/if.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
sys/net/if_var.h | 2 ++
2 files changed, 67 insertions(+)


diff --git a/sys/net/if.c b/sys/net/if.c
index 58711061eb5e..f3ef822178ff 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -4535,6 +4535,71 @@ if_foreach(if_foreach_cb_t cb, void *cb_arg)
return (error);
}


+/*
+ * Iterates over the list of interfaces, permitting callback function @cb to sleep.
+ * Stops iteration if @cb returns non-zero error code.
+ * Returns the last error code from @cb.
+ * @match_cb: optional match callback limiting the iteration to only matched interfaces
+ * @match_arg: argument to pass to @match_cb
+ * @cb: iteration callback
+ * @cb_arg: argument to pass to @cb
+ */
+int
+if_foreach_sleep(if_foreach_match_t match_cb, void *match_arg, if_foreach_cb_t cb,
+ void *cb_arg)
+{
+ int match_count = 0, array_size = 16; /* 128 bytes for malloc */
+ struct ifnet **match_array = NULL;
+ int error = 0;
+
+ MPASS(cb);
+
+ while (true) {
+ struct ifnet **new_array;
+ int new_size = array_size;
+ struct epoch_tracker et;
+ struct ifnet *ifp;
+
+ while (new_size < match_count)
+ new_size *= 2;
+ new_array = malloc(new_size * sizeof(void *), M_TEMP, M_WAITOK);
+ if (match_array != NULL)
+ memcpy(new_array, match_array, array_size * sizeof(void *));
+ free(match_array, M_TEMP);
+ match_array = new_array;
+ array_size = new_size;
+
+ match_count = 0;
+ NET_EPOCH_ENTER(et);
+ CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
+ if (match_cb != NULL && !match_cb(ifp, match_arg))
+ continue;
+ if (match_count < array_size) {
+ if (if_try_ref(ifp))
+ match_array[match_count++] = ifp;
+ } else
+ match_count++;
+ }
+ NET_EPOCH_EXIT(et);
+
+ if (match_count > array_size) {
+ for (int i = 0; i < array_size; i++)
+ if_rele(match_array[i]);
+ continue;
+ } else {
+ for (int i = 0; i < match_count; i++) {
+ if (error == 0)
+ error = cb(match_array[i], cb_arg);
+ if_rele(match_array[i]);
+ }
+ free(match_array, M_TEMP);
+ break;
+ }
+ }
+
+ return (error);
+}
+
u_int
if_foreach_lladdr(if_t ifp, iflladdr_cb_t cb, void *cb_arg)
{
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index c9b2de736d10..3e4d6c883c13 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -680,7 +680,9 @@ typedef u_int if_addr_cb_t(void *, struct ifaddr *, u_int);
u_int if_foreach_addr_type(if_t ifp, int type, if_addr_cb_t cb, void *cb_arg);


typedef int (*if_foreach_cb_t)(if_t, void *);
+typedef bool (*if_foreach_match_t)(if_t, void *);
int if_foreach(if_foreach_cb_t, void *);
+int if_foreach_sleep(if_foreach_match_t, void *, if_foreach_cb_t, void *);


/* Functions */
void if_setinitfn(if_t ifp, if_init_fn_t);