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MINOR: fd: add a new FD_DISOWN flag to prevent from closing a deleted FD

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Some FDs might be offered to some external code (external libraries)
which will deal with them until they close them. As such we must not
close them upon fd_delete() but we need to delete them anyway so that
they do not appear anymore in the fdtab. This used to be handled by
fd_remove() before 2.3 but we don't have this anymore.

This patch introduces a new flag FD_DISOWN to let fd_delete() know that
the core doesn't own the fd and it must not be closed upon removal from
the fd_tab. This way it's totally unregistered from the poller but still
open.

This patch must be backported on branches >= 2.3 because it will be
needed to fix a bug affecting SSL async. it should be adapted on 2.3
because state flags were stored in a different way (via bits in the
structure).

(cherry picked from commit f41a3f6762)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
This commit is contained in:
Emeric Brun 2022-07-01 17:31:25 +02:00 committed by Christopher Faulet
parent ac082b4194
commit 7e47164fe3
2 changed files with 7 additions and 1 deletions
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2
include/haproxy/fd-t.h
View File

@ -69,6 +69,7 @@ enum {
#define FD_ET_POSSIBLE_BIT 19 /* edge-triggered is possible on this FD */
#define FD_EXPORTED_BIT 20 /* FD is exported and must not be closed */
#define FD_EXCL_SYSCALL_BIT 21 /* a syscall claims exclusivity on this FD */
#define FD_DISOWN_BIT 22 /* this fd will be closed by some external code */
/* and flag values */
@ -109,6 +110,7 @@ enum {
#define FD_ET_POSSIBLE (1U << FD_ET_POSSIBLE_BIT)
#define FD_EXPORTED (1U << FD_EXPORTED_BIT)
#define FD_EXCL_SYSCALL (1U << FD_EXCL_SYSCALL_BIT)
#define FD_DISOWN (1U << FD_DISOWN_BIT)
/* FD update status after fd_update_events() */
enum {

6
src/fd.c
View File

@ -306,6 +306,9 @@ done:
*/
void _fd_delete_orphan(int fd)
{
uint fd_disown;
fd_disown = fdtab[fd].state & FD_DISOWN;
if (fdtab[fd].state & FD_LINGER_RISK) {
/* this is generally set when connecting to servers */
DISGUISE(setsockopt(fd, SOL_SOCKET, SO_LINGER,
@ -327,7 +330,8 @@ void _fd_delete_orphan(int fd)
/* perform the close() call last as it's what unlocks the instant reuse
* of this FD by any other thread.
*/
close(fd);
if (!fd_disown)
close(fd);
_HA_ATOMIC_DEC(&ha_used_fds);
}