From: Jonathan Lemon <[email protected]>
To: <[email protected]>
Subject: [RFC v1 6/9] io_uring: introduce reference tracking for user pages.
Date: Fri, 7 Oct 2022 14:17:10 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
This is currently a WIP.
If only part of a page is used by a skb fragment, and then provided
to the user, the page should not be reused by the kernel until all
sub-page fragments are not in use.
If only full pages are used (and not sub-page fragments), then this
code shouldn't be needed.
Signed-off-by: Jonathan Lemon <[email protected]>
---
io_uring/zctap.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/io_uring/zctap.c b/io_uring/zctap.c
index 58b4c5417650..9db3421fb9fa 100644
--- a/io_uring/zctap.c
+++ b/io_uring/zctap.c
@@ -183,9 +183,36 @@ struct ifq_region {
int count;
int imu_idx;
int nr_pages;
+ u8 *page_uref;
struct page *page[];
};
+static void io_add_page_uref(struct ifq_region *ifr, u16 pgid)
+{
+ if (WARN_ON(!ifr))
+ return;
+
+ if (WARN_ON(pgid < ifr->imu_idx))
+ return;
+
+ ifr->page_uref[pgid - ifr->imu_idx]++;
+}
+
+static bool io_put_page_last_uref(struct ifq_region *ifr, u64 addr)
+{
+ int idx;
+
+ if (WARN_ON(addr < ifr->start || addr > ifr->end))
+ return false;
+
+ idx = (addr - ifr->start) >> PAGE_SHIFT;
+
+ if (WARN_ON(!ifr->page_uref[idx]))
+ return false;
+
+ return --ifr->page_uref[idx] == 0;
+}
+
int io_provide_ifq_region_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
@@ -244,6 +271,11 @@ int io_provide_ifq_region(struct io_kiocb *req, unsigned int issue_flags)
if (!ifr)
return -ENOMEM;
+ ifr->page_uref = kvmalloc_array(nr_pages, sizeof(u8), GFP_KERNEL);
+ if (!ifr->page_uref) {
+ kvfree(ifr);
+ return -ENOMEM;
+ }
ifr->nr_pages = nr_pages;
ifr->imu_idx = idx;
@@ -261,6 +293,7 @@ int io_provide_ifq_region(struct io_kiocb *req, unsigned int issue_flags)
info = zctap_page_info(r->bgid, idx + i, id);
set_page_private(page, info);
ifr->page[i] = page;
+ ifr->page_uref[i] = 0;
}
WRITE_ONCE(r->ifq->region, ifr);
@@ -273,6 +306,7 @@ int io_provide_ifq_region(struct io_kiocb *req, unsigned int issue_flags)
set_page_private(page, 0);
}
+ kvfree(ifr->page_uref);
kvfree(ifr);
return -EEXIST;
--
2.30.2
next prev parent reply other threads:[~2022-10-07 21:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-07 21:17 [RFC v1 0/9] zero-copy RX for io_uring Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 1/9] io_uring: add zctap ifq definition Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 2/9] netdevice: add SETUP_ZCTAP to the netdev_bpf structure Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 3/9] io_uring: add register ifq opcode Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 4/9] io_uring: add provide_ifq_region opcode Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 5/9] io_uring: Add io_uring zctap iov structure and helpers Jonathan Lemon
2022-10-07 21:17 ` Jonathan Lemon [this message]
2022-10-07 21:17 ` [RFC v1 7/9] page_pool: add page allocation and free hooks Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 8/9] io_uring: provide functions for the page_pool Jonathan Lemon
2022-10-07 21:17 ` [RFC v1 9/9] io_uring: add OP_RECV_ZC command Jonathan Lemon
2022-10-10 7:37 ` [RFC v1 0/9] zero-copy RX for io_uring dust.li
2022-10-10 19:34 ` Jonathan Lemon
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