Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
1 年多 前同步成功

通知 163
Star 36
Fork 7
cloud-kernel
cloud-kernel
切换分支/标签
  1. 02 12月, 2017 3 次提交
    • S
      rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete · f10b4cff
      由 Sowmini Varadhan 提交于 
      The rds_tcp_kill_sock() function parses the rds_tcp_conn_list
to find the rds_connection entries marked for deletion as part
of the netns deletion under the protection of the rds_tcp_conn_lock.
Since the rds_tcp_conn_list tracks rds_tcp_connections (which
have a 1:1 mapping with rds_conn_path), multiple tc entries in
the rds_tcp_conn_list will map to a single rds_connection, and will
be deleted as part of the rds_conn_destroy() operation that is
done outside the rds_tcp_conn_lock.

The rds_tcp_conn_list traversal done under the protection of
rds_tcp_conn_lock should not leave any doomed tc entries in
the list after the rds_tcp_conn_lock is released, else another
concurrently executiong netns delete (for a differnt netns) thread
may trip on these entries.
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f10b4cff
    • S
      rds: tcp: correctly sequence cleanup on netns deletion. · 681648e6
      由 Sowmini Varadhan 提交于 
      Commit 8edc3aff ("rds: tcp: Take explicit refcounts on struct net")
introduces a regression in rds-tcp netns cleanup. The cleanup_net(),
(and thus rds_tcp_dev_event notification) is only called from put_net()
when all netns refcounts go to 0, but this cannot happen if the
rds_connection itself is holding a c_net ref that it expects to
release in rds_tcp_kill_sock.

Instead, the rds_tcp_kill_sock callback should make sure to
tear down state carefully, ensuring that the socket teardown
is only done after all data-structures and workqs that depend
on it are quiesced.

The original motivation for commit 8edc3aff ("rds: tcp: Take explicit
refcounts on struct net") was to resolve a race condition reported by
syzkaller where workqs for tx/rx/connect were triggered after the
namespace was deleted. Those worker threads should have been
cancelled/flushed before socket tear-down and indeed,
rds_conn_path_destroy() does try to sequence this by doing
     /* cancel cp_send_w */
     /* cancel cp_recv_w */
     /* flush cp_down_w */
     /* free data structures */
Here the "flush cp_down_w" will trigger rds_conn_shutdown and thus
invoke rds_tcp_conn_path_shutdown() to close the tcp socket, so that
we ought to have satisfied the requirement that "socket-close is
done after all other dependent state is quiesced". However,
rds_conn_shutdown has a bug in that it *always* triggers the reconnect
workq (and if connection is successful, we always restart tx/rx
workqs so with the right timing, we risk the race conditions reported
by syzkaller).

Netns deletion is like module teardown- no need to restart a
reconnect in this case. We can use the c_destroy_in_prog bit
to avoid restarting the reconnect.

Fixes: 8edc3aff ("rds: tcp: Take explicit refcounts on struct net")
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      681648e6
    • S
      rds: tcp: remove redundant function rds_tcp_conn_paths_destroy() · 2d746c93
      由 Sowmini Varadhan 提交于 
      A side-effect of Commit c14b0366 ("rds: tcp: set linger to 1
when unloading a rds-tcp") is that we always send a RST on the tcp
connection for rds_conn_destroy(), so rds_tcp_conn_paths_destroy()
is not needed any more and is removed in this patch.
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2d746c93
  3. 16 11月, 2017 1 次提交
  5. 10 11月, 2017 1 次提交
    • H
      rds: ib: Fix NULL pointer dereference in debug code · 1cb483a5
      由 Håkon Bugge 提交于 
      rds_ib_recv_refill() is a function that refills an IB receive
queue. It can be called from both the CQE handler (tasklet) and a
worker thread.

Just after the call to ib_post_recv(), a debug message is printed with
rdsdebug():

            ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
            rdsdebug("recv %p ibinc %p page %p addr %lu ret %d\n", recv,
                     recv->r_ibinc, sg_page(&recv->r_frag->f_sg),
                     (long) ib_sg_dma_address(
                            ic->i_cm_id->device,
                            &recv->r_frag->f_sg),
                    ret);

Now consider an invocation of rds_ib_recv_refill() from the worker
thread, which is preemptible. Further, assume that the worker thread
is preempted between the ib_post_recv() and rdsdebug() statements.

Then, if the preemption is due to a receive CQE event, the
rds_ib_recv_cqe_handler() will be invoked. This function processes
receive completions, including freeing up data structures, such as the
recv->r_frag.

In this scenario, rds_ib_recv_cqe_handler() will process the receive
WR posted above. That implies, that the recv->r_frag has been freed
before the above rdsdebug() statement has been executed. When it is
later executed, we will have a NULL pointer dereference:

[ 4088.068008] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 4088.076754] IP: rds_ib_recv_refill+0x87/0x620 [rds_rdma]
[ 4088.082686] PGD 0 P4D 0
[ 4088.085515] Oops: 0000 [#1] SMP
[ 4088.089015] Modules linked in: rds_rdma(OE) rds(OE) rpcsec_gss_krb5(E) nfsv4(E) dns_resolver(E) nfs(E) fscache(E) mlx4_ib(E) ib_ipoib(E) rdma_ucm(E) ib_ucm(E) ib_uverbs(E) ib_umad(E) rdma_cm(E) ib_cm(E) iw_cm(E) ib_core(E) binfmt_misc(E) sb_edac(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) kvm(E) irqbypass(E) crct10dif_pclmul(E) crc32_pclmul(E) ghash_clmulni_intel(E) pcbc(E) aesni_intel(E) crypto_simd(E) iTCO_wdt(E) glue_helper(E) iTCO_vendor_support(E) sg(E) cryptd(E) pcspkr(E) ipmi_si(E) ipmi_devintf(E) ipmi_msghandler(E) shpchp(E) ioatdma(E) i2c_i801(E) wmi(E) lpc_ich(E) mei_me(E) mei(E) mfd_core(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) ip_tables(E) ext4(E) mbcache(E) jbd2(E) fscrypto(E) mgag200(E) i2c_algo_bit(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E)
[ 4088.168486]  fb_sys_fops(E) ahci(E) ixgbe(E) libahci(E) ttm(E) mdio(E) ptp(E) pps_core(E) drm(E) sd_mod(E) libata(E) crc32c_intel(E) mlx4_core(E) i2c_core(E) dca(E) megaraid_sas(E) dm_mirror(E) dm_region_hash(E) dm_log(E) dm_mod(E) [last unloaded: rds]
[ 4088.193442] CPU: 20 PID: 1244 Comm: kworker/20:2 Tainted: G           OE   4.14.0-rc7.master.20171105.ol7.x86_64 #1
[ 4088.205097] Hardware name: Oracle Corporation ORACLE SERVER X5-2L/ASM,MOBO TRAY,2U, BIOS 31110000 03/03/2017
[ 4088.216074] Workqueue: ib_cm cm_work_handler [ib_cm]
[ 4088.221614] task: ffff885fa11d0000 task.stack: ffffc9000e598000
[ 4088.228224] RIP: 0010:rds_ib_recv_refill+0x87/0x620 [rds_rdma]
[ 4088.234736] RSP: 0018:ffffc9000e59bb68 EFLAGS: 00010286
[ 4088.240568] RAX: 0000000000000000 RBX: ffffc9002115d050 RCX: ffffc9002115d050
[ 4088.248535] RDX: ffffffffa0521380 RSI: ffffffffa0522158 RDI: ffffffffa0525580
[ 4088.256498] RBP: ffffc9000e59bbf8 R08: 0000000000000005 R09: 0000000000000000
[ 4088.264465] R10: 0000000000000339 R11: 0000000000000001 R12: 0000000000000000
[ 4088.272433] R13: ffff885f8c9d8000 R14: ffffffff81a0a060 R15: ffff884676268000
[ 4088.280397] FS:  0000000000000000(0000) GS:ffff885fbec80000(0000) knlGS:0000000000000000
[ 4088.289434] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4088.295846] CR2: 0000000000000020 CR3: 0000000001e09005 CR4: 00000000001606e0
[ 4088.303816] Call Trace:
[ 4088.306557]  rds_ib_cm_connect_complete+0xe0/0x220 [rds_rdma]
[ 4088.312982]  ? __dynamic_pr_debug+0x8c/0xb0
[ 4088.317664]  ? __queue_work+0x142/0x3c0
[ 4088.321944]  rds_rdma_cm_event_handler+0x19e/0x250 [rds_rdma]
[ 4088.328370]  cma_ib_handler+0xcd/0x280 [rdma_cm]
[ 4088.333522]  cm_process_work+0x25/0x120 [ib_cm]
[ 4088.338580]  cm_work_handler+0xd6b/0x17aa [ib_cm]
[ 4088.343832]  process_one_work+0x149/0x360
[ 4088.348307]  worker_thread+0x4d/0x3e0
[ 4088.352397]  kthread+0x109/0x140
[ 4088.355996]  ? rescuer_thread+0x380/0x380
[ 4088.360467]  ? kthread_park+0x60/0x60
[ 4088.364563]  ret_from_fork+0x25/0x30
[ 4088.368548] Code: 48 89 45 90 48 89 45 98 eb 4d 0f 1f 44 00 00 48 8b 43 08 48 89 d9 48 c7 c2 80 13 52 a0 48 c7 c6 58 21 52 a0 48 c7 c7 80 55 52 a0 <4c> 8b 48 20 44 89 64 24 08 48 8b 40 30 49 83 e1 fc 48 89 04 24
[ 4088.389612] RIP: rds_ib_recv_refill+0x87/0x620 [rds_rdma] RSP: ffffc9000e59bb68
[ 4088.397772] CR2: 0000000000000020
[ 4088.401505] ---[ end trace fe922e6ccf004431 ]---

This bug was provoked by compiling rds out-of-tree with
EXTRA_CFLAGS="-DRDS_DEBUG -DDEBUG" and inserting an artificial delay
between the rdsdebug() and ib_ib_port_recv() statements:

   	       /* XXX when can this fail? */
	       ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
+		if (can_wait)
+			usleep_range(1000, 5000);
	       rdsdebug("recv %p ibinc %p page %p addr %lu ret %d\n", recv,
			recv->r_ibinc, sg_page(&recv->r_frag->f_sg),
			(long) ib_sg_dma_address(

The fix is simply to move the rdsdebug() statement up before the
ib_post_recv() and remove the printing of ret, which is taken care of
anyway by the non-debug code.
Signed-off-by: NHåkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: NKnut Omang <knut.omang@oracle.com>
Reviewed-by: NWei Lin Guay <wei.lin.guay@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1cb483a5
  7. 02 11月, 2017 1 次提交
    • G
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      由 Greg Kroah-Hartman 提交于 
      Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: NPhilippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  9. 26 10月, 2017 2 次提交
  11. 06 10月, 2017 2 次提交
  13. 08 9月, 2017 1 次提交
  15. 06 9月, 2017 1 次提交
  17. 29 8月, 2017 1 次提交
  19. 09 8月, 2017 1 次提交
  21. 04 8月, 2017 1 次提交
  23. 21 7月, 2017 1 次提交
  25. 17 7月, 2017 1 次提交
    • S
      rds: cancel send/recv work before queuing connection shutdown · aed20a53
      由 Sowmini Varadhan 提交于 
      We could end up executing rds_conn_shutdown before the rds_recv_worker
thread, then rds_conn_shutdown -> rds_tcp_conn_shutdown can do a
sock_release and set sock->sk to null, which may interleave in bad
ways with rds_recv_worker, e.g., it could result in:

"BUG: unable to handle kernel NULL pointer dereference at 0000000000000078"
    [ffff881769f6fd70] release_sock at ffffffff815f337b
    [ffff881769f6fd90] rds_tcp_recv at ffffffffa043c888 [rds_tcp]
    [ffff881769f6fdb0] rds_recv_worker at ffffffffa04a4810 [rds]
    [ffff881769f6fde0] process_one_work at ffffffff810a14c1
    [ffff881769f6fe40] worker_thread at ffffffff810a1940
    [ffff881769f6fec0] kthread at ffffffff810a6b1e

Also, do not enqueue any new shutdown workq items when the connection is
shutting down (this may happen for rds-tcp in softirq mode, if a FIN
or CLOSE is received while the modules is in the middle of an unload)
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      aed20a53
  27. 08 7月, 2017 1 次提交
  29. 05 7月, 2017 4 次提交
  31. 01 7月, 2017 1 次提交
  33. 22 6月, 2017 2 次提交
  35. 17 6月, 2017 3 次提交
  37. 22 4月, 2017 1 次提交
  39. 06 4月, 2017 1 次提交
  41. 03 4月, 2017 2 次提交
  43. 14 3月, 2017 4 次提交
  45. 10 3月, 2017 2 次提交
    • D
      net: Work around lockdep limitation in sockets that use sockets · cdfbabfb
      由 David Howells 提交于 
      Lockdep issues a circular dependency warning when AFS issues an operation
through AF_RXRPC from a context in which the VFS/VM holds the mmap_sem.

The theory lockdep comes up with is as follows:

 (1) If the pagefault handler decides it needs to read pages from AFS, it
     calls AFS with mmap_sem held and AFS begins an AF_RXRPC call, but
     creating a call requires the socket lock:

	mmap_sem must be taken before sk_lock-AF_RXRPC

 (2) afs_open_socket() opens an AF_RXRPC socket and binds it.  rxrpc_bind()
     binds the underlying UDP socket whilst holding its socket lock.
     inet_bind() takes its own socket lock:

	sk_lock-AF_RXRPC must be taken before sk_lock-AF_INET

 (3) Reading from a TCP socket into a userspace buffer might cause a fault
     and thus cause the kernel to take the mmap_sem, but the TCP socket is
     locked whilst doing this:

	sk_lock-AF_INET must be taken before mmap_sem

However, lockdep's theory is wrong in this instance because it deals only
with lock classes and not individual locks.  The AF_INET lock in (2) isn't
really equivalent to the AF_INET lock in (3) as the former deals with a
socket entirely internal to the kernel that never sees userspace.  This is
a limitation in the design of lockdep.

Fix the general case by:

 (1) Double up all the locking keys used in sockets so that one set are
     used if the socket is created by userspace and the other set is used
     if the socket is created by the kernel.

 (2) Store the kern parameter passed to sk_alloc() in a variable in the
     sock struct (sk_kern_sock).  This informs sock_lock_init(),
     sock_init_data() and sk_clone_lock() as to the lock keys to be used.

     Note that the child created by sk_clone_lock() inherits the parent's
     kern setting.

 (3) Add a 'kern' parameter to ->accept() that is analogous to the one
     passed in to ->create() that distinguishes whether kernel_accept() or
     sys_accept4() was the caller and can be passed to sk_alloc().

     Note that a lot of accept functions merely dequeue an already
     allocated socket.  I haven't touched these as the new socket already
     exists before we get the parameter.

     Note also that there are a couple of places where I've made the accepted
     socket unconditionally kernel-based:

	irda_accept()
	rds_rcp_accept_one()
	tcp_accept_from_sock()

     because they follow a sock_create_kern() and accept off of that.

Whilst creating this, I noticed that lustre and ocfs don't create sockets
through sock_create_kern() and thus they aren't marked as for-kernel,
though they appear to be internal.  I wonder if these should do that so
that they use the new set of lock keys.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cdfbabfb
    • Z
      rds: ib: add error handle · 3b12f73a
      由 Zhu Yanjun 提交于 
      In the function rds_ib_setup_qp, the error handle is missing. When some
error occurs, it is possible that memory leak occurs. As such, error
handle is added.

Cc: Joe Jin <joe.jin@oracle.com>
Reviewed-by: NJunxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: NGuanglei Li <guanglei.li@oracle.com>
Signed-off-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3b12f73a
  47. 08 3月, 2017 2 次提交
    • S
      rds: tcp: Sequence teardown of listen and acceptor sockets to avoid races · b21dd450
      由 Sowmini Varadhan 提交于 
      Commit a93d01f5 ("RDS: TCP: avoid bad page reference in
rds_tcp_listen_data_ready") added the function
rds_tcp_listen_sock_def_readable()  to handle the case when a
partially set-up acceptor socket drops into rds_tcp_listen_data_ready().
However, if the listen socket (rtn->rds_tcp_listen_sock) is itself going
through a tear-down via rds_tcp_listen_stop(), the (*ready)() will be
null and we would hit a panic  of the form
  BUG: unable to handle kernel NULL pointer dereference at   (null)
  IP:           (null)
   :
  ? rds_tcp_listen_data_ready+0x59/0xb0 [rds_tcp]
  tcp_data_queue+0x39d/0x5b0
  tcp_rcv_established+0x2e5/0x660
  tcp_v4_do_rcv+0x122/0x220
  tcp_v4_rcv+0x8b7/0x980
    :
In the above case, it is not fatal to encounter a NULL value for
ready- we should just drop the packet and let the flush of the
acceptor thread finish gracefully.

In general, the tear-down sequence for listen() and accept() socket
that is ensured by this commit is:
     rtn->rds_tcp_listen_sock = NULL; /* prevent any new accepts */
     In rds_tcp_listen_stop():
         serialize with, and prevent, further callbacks using lock_sock()
         flush rds_wq
         flush acceptor workq
         sock_release(listen socket)
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b21dd450
    • S
      rds: tcp: Reorder initialization sequence in rds_tcp_init to avoid races · 16c09b1c
      由 Sowmini Varadhan 提交于 
      Order of initialization in rds_tcp_init needs to be done so
that resources are set up and destroyed in the correct synchronization
sequence with both the data path, as well as netns create/destroy
path. Specifically,

- we must call register_pernet_subsys and get the rds_tcp_netid
  before calling register_netdevice_notifier, otherwise we risk
  the sequence
    1. register_netdevice_notifier sets up netdev notifier callback
    2. rds_tcp_dev_event -> rds_tcp_kill_sock uses netid 0, and finds
       the wrong rtn, resulting in a panic with string that is of the form:

  BUG: unable to handle kernel NULL pointer dereference at 000000000000000d
  IP: rds_tcp_kill_sock+0x3a/0x1d0 [rds_tcp]
         :

- the rds_tcp_incoming_slab kmem_cache must be initialized before the
  datapath starts up. The latter can happen any time after the
  pernet_subsys registration of rds_tcp_net_ops, whose -> init
  function sets up the listen socket. If the rds_tcp_incoming_slab has
  not been set up at that time, a panic of the form below may be
  encountered

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000014
  IP: kmem_cache_alloc+0x90/0x1c0
     :
  rds_tcp_data_recv+0x1e7/0x370 [rds_tcp]
  tcp_read_sock+0x96/0x1c0
  rds_tcp_recv_path+0x65/0x80 [rds_tcp]
     :
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      16c09b1c