From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH 4.4 13/39] epoll: replace ->visited/visited_list with generation count
Date: Mon, 12 Oct 2020 15:26:43 +0200 [thread overview]
Message-ID: <20201012132628.777186931@linuxfoundation.org> (raw)
In-Reply-To: <20201012132628.130632267@linuxfoundation.org>
From: Al Viro <viro@zeniv.linux.org.uk>
commit 18306c404abe18a0972587a6266830583c60c928 upstream.
removes the need to clear it, along with the races.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/eventpoll.c | 26 +++++++-------------------
1 file changed, 7 insertions(+), 19 deletions(-)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -217,8 +217,7 @@ struct eventpoll {
struct file *file;
/* used to optimize loop detection check */
- int visited;
- struct list_head visited_list_link;
+ u64 gen;
};
/* Wait structure used by the poll hooks */
@@ -262,6 +261,8 @@ static long max_user_watches __read_most
*/
static DEFINE_MUTEX(epmutex);
+static u64 loop_check_gen = 0;
+
/* Used to check for epoll file descriptor inclusion loops */
static struct nested_calls poll_loop_ncalls;
@@ -277,9 +278,6 @@ static struct kmem_cache *epi_cache __re
/* Slab cache used to allocate "struct eppoll_entry" */
static struct kmem_cache *pwq_cache __read_mostly;
-/* Visited nodes during ep_loop_check(), so we can unset them when we finish */
-static LIST_HEAD(visited_list);
-
/*
* List of files with newly added links, where we may need to limit the number
* of emanating paths. Protected by the epmutex.
@@ -1696,13 +1694,12 @@ static int ep_loop_check_proc(void *priv
struct epitem *epi;
mutex_lock_nested(&ep->mtx, call_nests + 1);
- ep->visited = 1;
- list_add(&ep->visited_list_link, &visited_list);
+ ep->gen = loop_check_gen;
for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
epi = rb_entry(rbp, struct epitem, rbn);
if (unlikely(is_file_epoll(epi->ffd.file))) {
ep_tovisit = epi->ffd.file->private_data;
- if (ep_tovisit->visited)
+ if (ep_tovisit->gen == loop_check_gen)
continue;
error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
ep_loop_check_proc, epi->ffd.file,
@@ -1743,18 +1740,8 @@ static int ep_loop_check_proc(void *priv
*/
static int ep_loop_check(struct eventpoll *ep, struct file *file)
{
- int ret;
- struct eventpoll *ep_cur, *ep_next;
-
- ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
+ return ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
ep_loop_check_proc, file, ep, current);
- /* clear visited list */
- list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
- visited_list_link) {
- ep_cur->visited = 0;
- list_del(&ep_cur->visited_list_link);
- }
- return ret;
}
static void clear_tfile_check_list(void)
@@ -1956,6 +1943,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, in
error_tgt_fput:
if (full_check) {
clear_tfile_check_list();
+ loop_check_gen++;
mutex_unlock(&epmutex);
}
next prev parent reply other threads:[~2020-10-12 13:32 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 13:26 [PATCH 4.4 00/39] 4.4.239-rc1 review Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 01/39] gpio: tc35894: fix up tc35894 interrupt configuration Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 02/39] Input: i8042 - add nopnp quirk for Acer Aspire 5 A515 Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 03/39] drm/amdgpu: restore proper ref count in amdgpu_display_crtc_set_config Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 04/39] net: dec: de2104x: Increase receive ring size for Tulip Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 05/39] rndis_host: increase sleep time in the query-response loop Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 06/39] drivers/net/wan/lapbether: Make skb->protocol consistent with the header Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 07/39] drivers/net/wan/hdlc: Set skb->protocol before transmitting Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 08/39] nfs: Fix security label length not being reset Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 09/39] clk: samsung: exynos4: mark chipid clock as CLK_IGNORE_UNUSED Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 10/39] iommu/exynos: add missing put_device() call in exynos_iommu_of_xlate() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 11/39] i2c: cpm: Fix i2c_ram structure Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 12/39] epoll: do not insert into poll queues until all sanity checks are done Greg Kroah-Hartman
2020-10-12 13:26 ` Greg Kroah-Hartman [this message]
2020-10-12 13:26 ` [PATCH 4.4 14/39] epoll: EPOLL_CTL_ADD: close the race in decision to take fast path Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 15/39] ep_create_wakeup_source(): dentry name can change under you Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 16/39] netfilter: ctnetlink: add a range check for l3/l4 protonum Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 17/39] fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 18/39] Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 19/39] Revert "ravb: Fixed to be able to unload modules" Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 20/39] fbcon: Fix global-out-of-bounds read in fbcon_get_font() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 21/39] net: wireless: nl80211: fix out-of-bounds access in nl80211_del_key() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 22/39] usermodehelper: reset umask to default before executing user process Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 23/39] platform/x86: thinkpad_acpi: initialize tp_nvram_state variable Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 24/39] platform/x86: thinkpad_acpi: re-initialize ACPI buffer size when reuse Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 25/39] driver core: Fix probe_count imbalance in really_probe() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 26/39] perf top: Fix stdio interface input handling with glibc 2.28+ Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 27/39] sctp: fix sctp_auth_init_hmacs() error path Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 28/39] team: set dev->needed_headroom in team_setup_by_port() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 29/39] net: team: fix memory leak in __team_options_register Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 30/39] mtd: nand: Provide nand_cleanup() function to free NAND related resources Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 31/39] xfrm: clone XFRMA_REPLAY_ESN_VAL in xfrm_do_migrate Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 32/39] xfrm: clone whole liftime_cur structure " Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 33/39] net: stmmac: removed enabling eee in EEE set callback Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 34/39] xfrm: Use correct address family in xfrm_state_find Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 35/39] bonding: set dev->needed_headroom in bond_setup_by_slave() Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 36/39] rxrpc: Fix rxkad token xdr encoding Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 37/39] rxrpc: Downgrade the BUG() for unsupported token type in rxrpc_read() Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 38/39] rxrpc: Fix server keyring leak Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 39/39] net: usb: rtl8150: set random MAC address when set_ethernet_addr() fails Greg Kroah-Hartman
2020-10-13 8:46 ` [PATCH 4.4 00/39] 4.4.239-rc1 review Naresh Kamboju
2020-10-13 16:38 ` Guenter Roeck
2020-10-13 18:11 ` Pavel Machek
2020-10-14 7:47 ` Greg Kroah-Hartman
2020-10-14 10:18 ` Pavel Machek
2020-10-14 1:43 ` Shuah Khan
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