Commit Graph

256937 Commits

Author SHA1 Message Date
Konstantin Belousov
e2494f7561 atomic: add atomic_interrupt_fence()
with the semantic following C11 signal_fence, that is, it establishes
ordering between its place and any interrupt handler executing on the
same CPU.

Reviewed by:	markj, mjg, rlibby
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D28909
2021-02-24 22:45:24 +02:00
Brett Mastbergen
43d4dfac96 pwm_backlight: Add MODULE_DEPEND on backlight
Make the pwm_backlight module depend on backlight, so it
has access to the backlight interface symbols.  Otherwise you'll
get an error like:

link_elf: symbol backlight_get_info_desc undefined

Signed-off-by: Brett Mastbergen <brett.mastbergen@gmail.com>
MFC after:	3 days
PR: 		253765
2021-02-24 17:56:26 +01:00
Nathan Whitehorn
f7aebfbe5c Add GPT PREP-boot type to mkimg(1) from geom_gpt.
This partition type can be used to boot some PowerKVM VMs. We don't
support it well because of some limitations in SLOF, but it's worth at
least have feature parity in geom and mkimg.
2021-02-24 10:31:44 -05:00
Mark Johnston
b6999635b1 iflib: Avoid double counting in rxeof
iflib_rxeof() was counting everything twice.  This was introduced when
pfil hooks were added to the iflib receive path.  We want to count rx
packets/bytes before the pfil hooks are executed, so remove the counter
adjustments that are executed after.

PR:		253583
Reviewed by:	gallatin, erj
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D28900
2021-02-24 10:08:53 -05:00
Nathan Whitehorn
e70eb40271 Mount the ESP on /boot/efi in VM images.
This follows an earlier change (0b7472b3d8) for mounting the ESP from
systems set up through the installer and should be MFC'ed with it.
2021-02-24 08:18:07 -05:00
Konstantin Belousov
6f30ac9995 Call softdep_prealloc() before taking ffs_lock_ea(), if unlock is committing
softdep_prealloc() must be called to ensure enough journal space is
available, before ffs_extwrite(). Also it must be done before taking
ffs_lock_ea(), because it calls ffs_syncvnode(), potentially dropping
the vnode lock.

Reviewed by:	mckusick
Tested by:	pho
MFC after:      1 week
Sponsored by:   The FreeBSD Foundation
2021-02-24 09:55:21 +02:00
Konstantin Belousov
5e198e7646 ffs_close_ea: do not relock vnode under lock_ea
ffs_lock_ea is after the vnode lock, so vnode must not be relocked under
lock_ea. Move ffs_truncate() call in ffs_close_ea() after the lock_ea is
dropped, and only truncate to length zero, since this is the only mode
supported by ffs_truncate() for EAs. Previously code did truncation and
then write.

Zero the part of the ext area that is unused, if truncation is due but not
done because ea area is not zero-length.

Reviewed by:	mckusick
Tested by:	pho
MFC after:      1 week
Sponsored by:   The FreeBSD Foundation
2021-02-24 09:55:04 +02:00
Konstantin Belousov
c6d68ca842 ffs_vnops.c: style
Use local var to shorten ap->a_vp expression.

Reviewed by:	mckusick
Tested by:	pho
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2021-02-24 09:54:53 +02:00
Konstantin Belousov
4983146279 ffs: do not call softdep_prealloc() from UFS_BALLOC()
Do it in ffs_write(), where we can gracefuly handle relock and its
consequences. In particular, recheck the v_data to see if the vnode
reclamation ended, and return EBADF when we cannot proceed with the
write.

Reviewed by:	mckusick
Reported by:	pho
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2021-02-24 09:54:50 +02:00
Konstantin Belousov
cc9958bf22 ffs_reallocblks: change the guard for softdep_prealloc() call to DOINGSUJ()
instead of DOINGSOFTDEP().  The softdep_prealloc() function does nothing
in SU case.

Note that the call should be safe with regard to the vnode relock,
because it is called with MNT_NOWAIT, which does not descend into fsync.

Reviewed by:	mckusick
Tested by:	pho
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2021-02-24 09:54:30 +02:00
Cy Schubert
6e822e9957 rc: fix parse of $local_startup
77e1ccbee3 introduced parallel execution
of rc. It separated groups with line feeds (\n) and elements within
groups using spaces. This is a natural separation due to rcorder
using spaces and lines to separate elements within groups with groups
of services separated by line feeds.

77e1ccbee3 parses the output from rcorder
by setting $IFS. However it failed to reset $IFS to default ' \t\n'
prior to calling find_local_scripts_new(), causing find_local_scripts_new()
to fail parsing $local_startup for site-specific local rc scripts, i.e.
${LOCALBASE}/etc/rc.d. This caused daemons from ports and packages such
as postfix, dovecot, nut, and others in ${LOCALBASE} not to be started.

PR:		249192
MFC after:	3 week
X-MFC with:	77e1ccbee3
2021-02-23 21:12:49 -08:00
Rajesh Kumar M A
ec78688666 Update manpage for AMD 10GbE driver
Approved by: vmaffione, gallatin

Differential Revision: https://reviews.freebsd.org/D28724

MFC after:	1 week
2021-02-24 05:01:10 +00:00
Nathan Whitehorn
1af48800c2 Delete memstick images for PowerPC.
These images only ever worked on Apple Powermacs, which are now a very
old platform, and did so only for a very loose definition of "worked"
(they booted on a small subset of supported machines). Moreover, all
the machines they *did* boot on also would boot from a memstick made
by dd'ing an CD image to a flash drive. Since a flash drive prepared
in this way would also boot all the newer systems we support, the
memstick images were strictly less functional than the CD images, even
for booting from memory sticks.
Reviewed by:	jhibbits
MFC after:	1 week
2021-02-23 22:17:20 -05:00
Mark Johnston
1d44514fcd rmlock: Add a required compiler membar to the rlock slow path
The tracker flags need to be loaded only after the tracker is removed
from its per-CPU queue.  Otherwise, readers may fail to synchronize with
pending writers attempting to propagate priority to active readers, and
readers and writers deadlock on each other.  This was observed in a
stable/12-based armv7 kernel where the compiler had reordered the load
of rmp_flags to before the stores updating the queue.

Reviewed by:	rlibby, scottl
Discussed with:	kib
Sponsored by:	Rubicon Communications, LLC ("Netgate")
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D28821
2021-02-23 21:17:12 -05:00
Mark Johnston
6ab923cbca pam_login_access: Fix negative entry matching logic
PR:		252194
Approved by:	so
Security:	CVE-2020-25580
Security:	FreeBSD-SA-21:03.pam_login_access
2021-02-23 19:14:05 -05:00
Allan Jude
6d67af5f8e Revert "ipmi_smbios: Deduplicate smbios entry point discovery logic"
This depends on another commit that has not landed yet, and broke the build

This reverts commit ba6e37e47f.
2021-02-23 22:49:13 +00:00
Allan Jude
4a5dfded17 Revert "ipmi_smbios: remove unused smbios_cksum function"
This reverts commit d2589dc3d5.
2021-02-23 22:48:59 +00:00
Alexander V. Chernikov
9c4a8d24f0 Fix nd6 rib_action() handling.
rib_action() guarantees valid rc filling IFF it returns without error.
Check rib_action() return code instead of checking rc fields.

PR:		253800
Reported by:	Frederic Denis <freebsdml@hecian.net>
MFC after:	immediately
2021-02-23 22:40:01 +00:00
Vladimir Kondratyev
bbacb7ce72 ig4: Add PCI IDs for Intel Gemini Lake I2C controller.
Submitted by:	Dmitry Luhtionov
MFC after:	2 weeks
2021-02-24 01:23:43 +03:00
Daniel Ebdrup Jensen
408edcca07 rc.conf(5): Add note about parallel startup variable
The commit below added parallel service startup, and it needs to be
documented, so people know about it.

PR:		249192
MFC with:	77e1ccbee3

Reviewed by:	yuripv
Differential Revision:	https://reviews.freebsd.org/D28898
2021-02-23 22:26:31 +01:00
Allan Jude
d2589dc3d5 ipmi_smbios: remove unused smbios_cksum function
Sponsored By:	Ampere Computing LLC
Submitted By:	Klara Inc.
Differential Revision:	https://reviews.freebsd.org/D28751
2021-02-23 21:24:47 +00:00
Nathan Whitehorn
0b7472b3d8 Mount the EFI system partition (ESP) on newly-installed systems.
Per hier(7), the ESP will be mounted at /boot/efi. On UFS systems,
any existing ESP will be reused and mounted there; otherwise, a new one
will be made. On ZFS systems, space for an ESP is allocated on all disks
in the root pool, but only the partition actually used to boot is set up
and mounted.

This makes future upgrades of the EFI loader easier (upgrade scripts can
just change /boot/efi) and also greatly simplifies the parts of the
installer involved in initialization of the ESP. It also makes the
installer's behavior correspond to the documentation in hier(7).

Reviewed by:		imp, tsoome
MFC after:		1 week
Relnotes:		yes
Differential Revision:	https://reviews.freebsd.org/D28897
2021-02-23 16:24:21 -05:00
Allan Jude
ba6e37e47f ipmi_smbios: Deduplicate smbios entry point discovery logic
Sponsored by:	Ampere Computing LLC
Submitted by:	Klara Inc.
Reviewed by:	imp
Differential Revision:	https://reviews.freebsd.org/D28743
2021-02-23 21:17:37 +00:00
Allan Jude
d0673fe160 smbios: Move smbios driver out from x86 machdep code
Add it to the x86 GENERIC and MINIMAL kernels

Sponsored by:	Ampere Computing LLC
Submitted by:	Klara Inc.
Reviewed by:	rpokala
Differential Revision:	https://reviews.freebsd.org/D28738
2021-02-23 21:17:09 +00:00
Dimitry Andric
cf97d2a1da Build lib/msun tests with compiler builtins disabled
This forces the compiler to emit calls to libm functions, instead of
possibly substituting pre-calculated results at compile time, which
should help to actually test those functions.

Reviewed by:	emaste, arichardson, ngie
Differential Revision: https://reviews.freebsd.org/D28577
MFC after:	3 days
2021-02-23 21:10:01 +01:00
Allan Jude
11ba8488b8 iicsmb: Request the bus recursively in bread()
ipmi_ssif will `smbus_request_bus()` to do multiple smbus requests
(which requests the iicbus), and then here in `bread()` we also need to
request the bus because `bread()` takes multiple transactions.
This causes deadlock as it's waiting for the bus it already has without
`IIC_RECURSIVE`.

Sponsored by:	Ampere Computing LLC
Submitted by:	Klara Inc.
Reviewed by:	imp
Differential Revision:	https://reviews.freebsd.org/D28742
2021-02-23 20:06:16 +00:00
Warner Losh
6b7580f7b1 camcontrol: change hueristic for I/O-less devtype
Some SATA drives have 'config' set to 0 in the identify block. Rather than rely
on it, use the strings windows uses to display the drive since they are supposed
to be space padded and will always be non-zero.
2021-02-23 12:56:15 -07:00
Daniel Ebdrup Jensen
ef1a1fc7e8 release(7) Fix mistake noted in review
I missed this when doing the final pass.

Fixes: f695e960 release(7): Remove stray references to DOC* variables
2021-02-23 19:11:54 +01:00
Konstantin Belousov
3ae8d83d04 Remove __NO_TLS.
All supported platforms support thread-local vars and __thread.

Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D28796
2021-02-23 20:08:10 +02:00
Daniel Ebdrup Jensen
f695e96067 release(7): Remove stray references to DOC* variables
We now live in the world of git, and release(7) should reflect that.

As of the commit referenced below, release images also no longer
include (stale) documentation, as the documentation has moved to
AsciiDoctor. This means that a few environment variables no longer
make sense, so remove them from their sections and mention them in
the compatibility section instead.

While here, also pet mandoc.

PR: 253615
MFC after: 3 days
MFC with: f61e92ca5a release: permanently remove the 'reldoc'
target and associates

Reviewed by:	gjb, lwhsu, yuripv
Differential Revision:	https://reviews.freebsd.org/D28881
2021-02-23 19:06:36 +01:00
Alex Richardson
fa32350347 close_range: add audit support
This fixes the closefrom test in sys/audit.

Includes cherry-picks of the following commits from openbsm:

4dfc628aaf
99ff6fe32a
da48a0399e

Reviewed By:	kevans
Differential Revision: https://reviews.freebsd.org/D28388
2021-02-23 17:47:07 +00:00
Alex Richardson
3775ddcf5a tests/sys/netgraph: Tell kyua that perl is required
Otherwise these tests fail with incomprehensible error messages.

Reviewed By:	kp
Differential Revision: https://reviews.freebsd.org/D28894
2021-02-23 17:43:31 +00:00
Daniel Ebdrup Jensen
75e6f664c4 find(1): Mark -not as an extensions to POSIX
While here, change mdoc macro from Ic to Fl.

PR:		253499
Reported by:	Michael Siegel <bugcounterism at malbolge.net>
2021-02-23 17:15:35 +01:00
Alexander Motin
7d4c444374 Bump CTL block backend threads from 14 to 32 per LUN.
This makes random read benchmarks look better on a wide ZFS pools.
I am not sure where the original value goes from, but it is there
for too long now.

MFC after:	1 week
2021-02-23 11:03:32 -05:00
Roger Pau Monné
0eaa97f0e8 stand/multiboot2: fix header length check
Check whether we have reached the end of the buffer using search_size
instead of MULTIBOOT_SEARCH, which is the maximum defined by the
specification, but the file can be shorter than that.

This prevents printing a harmless error message when loading a file
that is smaller than MULTIBOOT_SEARCH.

Sponsored by: Citrix Systems R&D
MFC after: 3 days
Fixes: adda2797eb ('stand/multiboot2: add support for booting a Xen dom0 in UEFI mode')
2021-02-23 16:05:03 +01:00
Roger Pau Monné
ab379c15af stand/multiboot2: fix error message format
Add a missing space in one error message.

Sponsored by: Citrix Systems R&D
MFC after: 3 days
Fixes: adda2797eb ('stand/multiboot2: add support for booting a Xen dom0 in UEFI mode')
2021-02-23 16:04:58 +01:00
Kristof Provost
26492ba271 bridge tests: Test STP on top of VLAN devices
This is basically the same test as the existing STP test, but now on top
of VLAN interfaces instead of directly using the epair devices.

MFC after:	1 week
Sponsored by:	Orange Business Services
Differential Revision:	https://reviews.freebsd.org/D28861
2021-02-23 13:54:07 +01:00
Kristof Provost
c139b3c19b arp/nd: Cope with late calls to iflladdr_event
When tearing down vnet jails we can move an if_bridge out (as
part of the normal vnet_if_return()). This can, when it's clearing out
its list of member interfaces, change its link layer address.
That sends an iflladdr_event, but at that point we've already freed the
AF_INET/AF_INET6 if_afdata pointers.

In other words: when the iflladdr_event callbacks fire we can't assume
that ifp->if_afdata[AF_INET] will be set.

Reviewed by:	donner@, melifaro@
MFC after:	1 week
Sponsored by:	Orange Business Services
Differential Revision:	https://reviews.freebsd.org/D28860
2021-02-23 13:54:07 +01:00
Kristof Provost
38c0951386 bridge: Remove members when assigned to a new vnet
When the bridge is moved to a different vnet we must remove all of its
member interfaces (and span interfaces), because we don't know if those
will be moved along with it. We don't want to hold references to
interfaces not in our vnet.

Reviewed by:	donner@
MFC after:	1 week
Sponsored by:	Orange Business Services
Differential Revision:	https://reviews.freebsd.org/D28859
2021-02-23 13:54:07 +01:00
Kristof Provost
89fa9c34d7 bridge/stp: Ensure we enter NET_EPOCH whenever we can send traffic
Reviewed by:	donner@
MFC after:	1 week
Sponsored by:	Orange Business Services
Differential Revision:	https://reviews.freebsd.org/D28858
2021-02-23 13:54:07 +01:00
Kristof Provost
711ed156b9 bridge: Support STP on VLAN devices
VLAN devices have type IFT_L2VLAN, so the STP code mistakenly believed
they couldn't be used for STP. That's not the case, so add the
ITF_L2VLAN to the check.

Reviewed by:	donner@
MFC after:	1 week
Sponsored by:	Orange Business Services
Differential Revision:	https://reviews.freebsd.org/D28857
2021-02-23 13:54:06 +01:00
Chris Rees
d27999e513 Create dhclient pid directory if it doesn't exist
- Upgrading from older FreeBSD versions can result in errors

 - /var/run can be a tmpfs, and this should be handled correctly

Approved by:		markj
Differential Revision:	https://reviews.freebsd.org/D28843
MFC after:		2 weeks
2021-02-23 13:19:44 +00:00
Rick Parrish
77e1ccbee3 rc: implement parallel boot
take advantage of the rcorder -p argument to implement parallel
booting in rc.

According to the author non scientific tests:
on a Core 2 Duo with spinning disk:

| Services enabled | before | after | saving |
| 0                | 8s     | 8s    | 0      |
| 1                | 13s    | 13s   | 0      |
| 2                | 17s    | 13s   | 5      |
| 3                | 23s    | 13s   | 10     |
| 4                | 28s    | 13s   | 15     |
| 5                | 33s    | 13s   | 20     |

PR:		249192
MFC after:	3 weeks
2021-02-23 11:16:53 +01:00
Alex Richardson
f3f7b0dc06 lib/msun/ctrig_test: Print the mismatched values on failure
This test fails on aarch64 but debugging it is difficult without the
results being printed.

Now the failing AArch64 test prints:
root@freebsd-aarch64:/nfsroot/usr/tests/lib/msun # kyua debug ctrig_test:test_nan_inputs
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: (ctan)(_d) (0 + -1 I) != expected (-0 + -1 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: ctan fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: (ctan)(_d) (0 + 1 I) != expected (-0 + 1 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: ctan fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: (ctanf)(_d) (0 + -1 I) != expected (-0 + -1 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: ctanf fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: (ctanf)(_d) (0 + 1 I) != expected (-0 + 1 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:211: ctanf fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: (ctanh)(_d) (1 + 0 I) != expected (1 + -0 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: ctanh fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: (ctanhf)(_d) (1 + 0 I) != expected (1 + -0 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: ctanhf fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: (ctanh)(_d) (-1 + 0 I) != expected (-1 + -0 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: ctanh fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: (ctanhf)(_d) (-1 + 0 I) != expected (-1 + -0 I)
*** Check failed: /local/scratch/alr48/cheri/freebsd/lib/msun/tests/ctrig_test.c:217: ctanhf fetestexcept((0x00000002 | 0x00000010 | 0x00000001 | 0x00000004 | 0x00000008)) (0x10) != 0
ctrig_test:test_nan_inputs  ->  failed: 16 checks failed; see output for more details

Reviewed By:	ngie
Differential Revision: https://reviews.freebsd.org/D28788
2021-02-23 09:39:40 +00:00
Eric Joyner
a7ac518bff ice_ddp: Update package file to 1.3.19.0
This package is intended to be used with ice(4) version 0.28.1-k.
That update will happen in a forthcoming commit.

Signed-off-by: Eric Joyner <erj@FreeBSD.org>
Sponsored by: Intel Corporation
2021-02-22 18:02:19 -08:00
Jamie Gritton
0a2a96f35a jail: Don't allow jails under dying parents
If a jail is created with jail_set(...JAIL_DYING), and it has a parent
currently in a dying state, that will bring the parent jail back to
life.  Restrict that to require that the parent itself be explicitly
brought back first, and not implicitly created along with the new
child jail.

Differential Revision:	https://reviews.freebsd.org/D28515
2021-02-22 17:04:06 -08:00
Mateusz Guzik
7f06b217c5 amd64: import asm strlen into libc
Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D28845
2021-02-23 00:09:55 +00:00
Jamie Gritton
701d6b50ae jail: Fix a LOR introduced in 1158508a80 2021-02-22 15:51:10 -08:00
Alexander V. Chernikov
5964172837 Simplify ifa/ifp refcounting in the routing stack.
The routing stack control depends on quite a tree of functions to
 determine the proper attributes of a route such as a source address (ifa)
 or transmit ifp of a route.

When actually inserting a route, the stack needs to ensure that ifa and ifp
 points to the entities that are still valid.
Validity means slightly more than just pointer validity - stack need guarantee
 that the provided objects are not scheduled for deletion.

Currently, callers either ignore it (most ifp parts, historically) or try to
 use refcounting (ifa parts). Even in case of ifa refcounting it's not always
 implemented in fully-safe manner. For example, some codepaths inside
 rt_getifa_fib() are referencing ifa while not holding any locks, resulting in
 possibility of referencing scheduled-for-deletion ifa.

Instead of trying to fix all of the callers by enforcing proper refcounting,
 switch to a different model.
As the rib_action() already requires epoch, do not require any stability guarantees
 other than the epoch-provided one.
Use newly-added conditional versions of the refcounting functions
 (ifa_try_ref(), if_try_ref()) and fail if any of these fails.

Reviewed by:	donner
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D28837
2021-02-22 23:37:59 +00:00
Alexander V. Chernikov
7563019bc6 Add if_try_ref() to simplify refcount handling inside epoch.
When we have an ifp pointer and the code is running inside epoch,
 epoch guarantees the pointer will not be freed.
However, the following case can still happen:

* in thread 1 we drop to refcount=0 for ifp and schedule its deletion.
* in thread 2 we use this ifp and reference it
* destroy callout kicks in
* unhappy user reports a bug

This can happen with the current implementation of ifnet_byindex_ref(),
 as we're not holding any locks preventing ifnet deletion by a parallel thread.

To address it, add if_try_ref(), allowing to return failure when
 referencing ifp with refcount=0.
Additionally, enforce existing if_ref() is with KASSERT to provide a
 cleaner error in such scenarios.

Finally, fix ifnet_byindex_ref() by using if_try_ref() and returning NULL
 if the latter fails.

MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D28836
2021-02-22 23:37:59 +00:00