Hello Chris,
Am 02.03.21 um 01:03 schrieb Chris Johns:
On 1/3/21 7:24 pm, Christian MAUDERER wrote:
Hello Chris,
thanks for the review.
Am 26.02.21 um 19:04 schrieb Chris Johns:
On 26/2/21 2:01 am, Christian Mauderer wrote:
Dynamically allocate a big enough file descriptor set for select(). A
better solution would be to use kqueue() instead of select().
---
.../racoon/rtems-bsd-racoon-session-data.h | 6 +--
ipsec-tools/src/racoon/session.c | 40 +++++++++++++++++++
2 files changed, 43 insertions(+), 3 deletions(-)
diff --git a/ipsec-tools/src/racoon/rtems-bsd-racoon-session-data.h
b/ipsec-tools/src/racoon/rtems-bsd-racoon-session-data.h
index b869a1518..196107a35 100644
--- a/ipsec-tools/src/racoon/rtems-bsd-racoon-session-data.h
+++ b/ipsec-tools/src/racoon/rtems-bsd-racoon-session-data.h
@@ -2,11 +2,11 @@
#include <rtems/linkersets.h>
#include "rtems-bsd-racoon-data.h"
/* session.c */
-RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static fd_set active_mask);
-RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static fd_set preset_mask);
+RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static _types_fd_set
*allocated_active_mask);
+RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static _types_fd_set
*allocated_preset_mask);
RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static int nfds);
RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static int signals[]);
RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static sig_atomic_t volatile
volatile sigreq[]);
-RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static struct fd_monitor
fd_monitors[]);
+RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static struct fd_monitor
*allocated_fd_monitors);
RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static struct fd_monitor_list
fd_monitor_tree[]);
RTEMS_LINKER_RWSET_CONTENT(bsd_prog_racoon, static struct sched scflushsa);
diff --git a/ipsec-tools/src/racoon/session.c b/ipsec-tools/src/racoon/session.c
index 65124c15e..90120c761 100644
--- a/ipsec-tools/src/racoon/session.c
+++ b/ipsec-tools/src/racoon/session.c
@@ -65,6 +65,10 @@
#include <sys/stat.h>
#include <paths.h>
#include <err.h>
+#ifdef __rtems__
+#include <sys/param.h>
+#include <rtems/libio_.h>
+#endif /* __rtems__ */
#include <netinet/in.h>
#include <resolv.h>
@@ -123,8 +127,16 @@ static void check_sigreq __P((void));
static void check_flushsa __P((void));
static int close_sockets __P((void));
+#ifndef __rtems__
static fd_set preset_mask, active_mask;
static struct fd_monitor fd_monitors[FD_SETSIZE];
+#else /* __rtems__ */
+static fd_set *allocated_preset_mask, *allocated_active_mask;
+static struct fd_monitor *allocated_fd_monitors;
+#define preset_mask (*allocated_preset_mask)
+#define active_mask (*allocated_active_mask)
+#define fd_monitors (allocated_fd_monitors)
+#endif /* __rtems__ */
static TAILQ_HEAD(fd_monitor_list, fd_monitor)
fd_monitor_tree[NUM_PRIORITIES];
static int nfds = 0;
@@ -134,7 +146,11 @@ static struct sched scflushsa = SCHED_INITIALIZER();
void
monitor_fd(int fd, int (*callback)(void *, int), void *ctx, int priority)
{
+#ifndef __rtems__
if (fd < 0 || fd >= FD_SETSIZE) {
+#else /* __rtems__ */
+ if (fd < 0 || fd >= rtems_libio_number_iops) {
+#endif /* __rtems__ */
plog(LLV_ERROR, LOCATION, NULL, "fd_set overrun");
exit(1);
}
@@ -158,7 +174,11 @@ monitor_fd(int fd, int (*callback)(void *, int), void
*ctx, int priority)
void
unmonitor_fd(int fd)
{
+#ifndef __rtems__
if (fd < 0 || fd >= FD_SETSIZE) {
+#else /* __rtems__ */
+ if (fd < 0 || fd >= rtems_libio_number_iops) {
+#endif /* __rtems__ */
plog(LLV_ERROR, LOCATION, NULL, "fd_set overrun");
exit(1);
}
@@ -186,7 +206,22 @@ session(void)
struct fd_monitor *fdm;
nfds = 0;
+#ifndef __rtems__
FD_ZERO(&preset_mask);
+#else /* __rtems__ */
+ allocated_preset_mask = calloc(sizeof(fd_set),
+ howmany(rtems_libio_number_iops, sizeof(fd_set) * 8));
Does `maxfiles` work here?
To be honest: I'm not sure.
According to the comment in file.h:
extern int maxfiles; /* kernel limit on number of open files */
Yes.
Sounds like it _can_ be the same as the maximum file number but doesn't have to.
I think we need to have them be the same value.
I didn't find where we implement it. It's declared as an extern int maxfiles but
I didn't find any definition. I found it only in libbsd in
freebsd/sys/kern/uipc_socket.c where it is defined like follows:
#define maxfiles rtems_libio_number_iops
Ah OK. I knew it had been assigned somewhere and yes it looks like it is local
to that file.
So question is: Where and how is maxfiles defined?
I have provided a value in the rtemsbsd init file as part of the set og globals
we need to maintained.
Somehow I missed that. Where can I find it?
+ if (allocated_preset_mask == NULL)
+ errx(1, "failed to allocate preset_mask");
+ allocated_active_mask = calloc(sizeof(fd_set),
+ howmany(rtems_libio_number_iops, sizeof(fd_set) * 8));
+ if (allocated_active_mask == NULL)
+ errx(1, "failed to allocate active_mask");
+ allocated_fd_monitors = calloc(
+ rtems_libio_number_iops, sizeof(struct fd_monitor));
+ if (allocated_fd_monitors == NULL)
+ errx(1, "failed to allocate fd_monitors");
At the core of this issue is the rotating fd allocation that we have in libio. A
report from a FreeBSD machine I have is:
$ sysctl -a | grep maxfiles
kern.maxfiles: 1037243
kern.maxfilesperproc: 933516
I doubt a select process in FreeBSD needs a select array with that many bits. I
have added similar code else where but I am wondering if this is really what we
want to do. A side effect for us is the stack usage is not bounded and that is a
problem. I think our newlib based max setting is too small.
I think we have to distinguish between FreeBSD kernel space and user space. If I
have seen it correctly, FreeBSD uses kqueues or maybe sometimes poll instead of
select in kernel space most of the time. That avoids the problem with big file
numbers.
Yes kqueue is nice but we need to support existing code and this is a primary
role libbsd needs to perform. The lack is signals in libbsd is another source of
issue.
I didn't want to say that we should not support select. I only wanted to
say that FreeBSD most likely just avoids that problem in kernel space so
that they don't have to support a select with 1037243 files. In user
space they limit a select to 1024 files.
Default for FreeBSD seems to be a FD_SETSIZE of 1024. See the Notes section in
the select man page:
https://www.freebsd.org/cgi/man.cgi?query=select&sektion=2&manpath=freebsd-release-ports#end
Yes.
I think select is used in user space applications most of the time. I would
guess that FreeBSD has some file number mapping between kernel and user space
that would allow every application to open 1024 files.
Yes. There are other checks and arrays in the kernel's select that handle the
size of 1024 or smaller. We should align ourselves with FreeBSD. A select call
uses a lot of stack.
I have no problem if we align more with FreeBSD. But I'm not sure how
much effort that would be. And we have to be careful not to increase the
memory usage for small targets too much.
FYI I have a major set of changes to libbsd that enables FreeBSD descriptor
support and moves the libio support to specific interfaces.
OK. When do you plan to add that and to which branches?
I am looking 6-freebsd-12 and master. Thses changes are a major rework and not
suitable for 5.
I assumed that.
I would like to add this
patch set to 5 sooner or later because it fixes a potential bug in racoon for
that branch too.
Sorry I missed this for 5. I will need to think about this on 5. I do not think
it is a problem but I am not sure about it on 6 and beyond. I would prefer we
consider a better fix for select that the limited 64 descriptors we currently
have.
Maybe we should take a multi step approach:
Use the workaround like I suggested for 5 and (at the moment) for
master. A similar workaround is already used in quite some other
locations in libbsd. So it's not a new method.
Start a ticket and a discussion for a better solution. I'm not sure yet
how that could look like. Some impressions from other systems:
- FreeBSD, OpenBSD, NetBSD and DragonFly BSD are using the same method
we use (or most likely the other way round) only with different FD_SETSIZEs:
https://cgit.freebsd.org/src/tree/sys/sys/select.h
https://github.com/NetBSD/src/blob/trunk/sys/sys/fd_set.h
https://github.com/openbsd/src/blob/master/sys/sys/select.h
https://gitweb.dragonflybsd.org/dragonfly.git/blob/HEAD:/sys/sys/_fd_set.h
- Linux Kernels nolibc.h used in Tests does the same again (GPL or MIT):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/include/nolibc/nolibc.h#n2522
- Apple is the same again. I'm not sure about the Apple license
therefore no link here so I don't spoil anyone beneath myself.
There are others that could be worth a look like Haiku, Musl-Libc, and
so on. But my general impression is that there is no much better
solution at least in the bigger systems except for avoiding select or
setting a bigger FD_SETSIZE. The most common ones seem to be 256 or
1024. But that only moves the problem a bit further away.
The changes I have
made are in tarballs in nfsv4 in my ftp area. The support includes the mapping
of libio descriptors to FB ones. The benefit of these changes is VFS and FreeBSD
file system support.
FreeBSD file system support sounds like a great feature. It would allow access
to a whole bunch of stable and well tested file system implementations.
It does. I have NFSv4 up and running.
Great to hear.
Best regards
Christian
Chris
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