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DupAcks in MPTCP #250

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Cowboy-Suman opened this issue Mar 21, 2018 · 1 comment
Open

DupAcks in MPTCP #250

Cowboy-Suman opened this issue Mar 21, 2018 · 1 comment

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@Cowboy-Suman
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Cowboy-Suman commented Mar 21, 2018

Hello,
I am trying to test a few mptcp schedulers in mininet. I need to check the out-of-order packets in each of the schedulers. I am using iperf in both the host in my mininet topology. I am using Wireshark (v2.4.5) in one of the host. Wireshark version 2.4.5 allows mptcp analysis.
We know that mptcp uses different sequence numbers for each of the subflows (in my case 2 subflows) and not a single sequence number for all the subflows. However in wireshark-> mptcp_analysis, there is the Data Sequence Number (DSN) available. I thought with the DSN it would be possible to check the out-of-order packets at the receiver host but even DSN is different for both the subflows. Moreover, when I use a single subflow the DSN is not equal to the normal sequence no. of the packet. So how can I check the out-of-order packets or DupAcks in this case? Am I doing anything wrong? Any advice will be helpful :-)

dreibh pushed a commit to dreibh/mptcp that referenced this issue Apr 20, 2018
commit 7972326 upstream.

This can be reproduced by bind/unbind the driver multiple times
in AM3517 board.

Analysis revealed that rtl8187_start() was invoked before probe
finishes(ie. before the mutex is initialized).

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty multipath-tcp#250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 [<c010e0d8>] (unwind_backtrace) from [<c010beac>] (show_stack+0x10/0x14)
 [<c010beac>] (show_stack) from [<c017401c>] (register_lock_class+0x4f4/0x55c)
 [<c017401c>] (register_lock_class) from [<c0176fe0>] (__lock_acquire+0x74/0x1938)
 [<c0176fe0>] (__lock_acquire) from [<c0178cfc>] (lock_acquire+0xfc/0x23c)
 [<c0178cfc>] (lock_acquire) from [<c08aa2f8>] (mutex_lock_nested+0x50/0x3b0)
 [<c08aa2f8>] (mutex_lock_nested) from [<c05f5bf8>] (rtl8187_start+0x2c/0xd54)
 [<c05f5bf8>] (rtl8187_start) from [<c082dea0>] (drv_start+0xa8/0x320)
 [<c082dea0>] (drv_start) from [<c084d1d4>] (ieee80211_do_open+0x2bc/0x8e4)
 [<c084d1d4>] (ieee80211_do_open) from [<c069be94>] (__dev_open+0xb8/0x120)
 [<c069be94>] (__dev_open) from [<c069c11c>] (__dev_change_flags+0x88/0x14c)
 [<c069c11c>] (__dev_change_flags) from [<c069c1f8>] (dev_change_flags+0x18/0x48)
 [<c069c1f8>] (dev_change_flags) from [<c0710b08>] (devinet_ioctl+0x738/0x840)
 [<c0710b08>] (devinet_ioctl) from [<c067925c>] (sock_ioctl+0x164/0x2f4)
 [<c067925c>] (sock_ioctl) from [<c02883f8>] (do_vfs_ioctl+0x8c/0x9d0)
 [<c02883f8>] (do_vfs_ioctl) from [<c0288da8>] (SyS_ioctl+0x6c/0x7c)
 [<c0288da8>] (SyS_ioctl) from [<c0107760>] (ret_fast_syscall+0x0/0x1c)
 Unable to handle kernel NULL pointer dereference at virtual address 00000000
 pgd = cd1ec000
 [00000000] *pgd=8d1de831, *pte=00000000, *ppte=00000000
 Internal error: Oops: 817 [#1] PREEMPT ARM
 Modules linked in:
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty multipath-tcp#250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 task: ce73eec0 task.stack: cd1ea000
 PC is at mutex_lock_nested+0xe8/0x3b0
 LR is at mutex_lock_nested+0xd0/0x3b0

Cc: [email protected]
Signed-off-by: Sudhir Sreedharan <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
dreibh pushed a commit to dreibh/mptcp that referenced this issue Apr 24, 2018
commit 7972326 upstream.

This can be reproduced by bind/unbind the driver multiple times
in AM3517 board.

Analysis revealed that rtl8187_start() was invoked before probe
finishes(ie. before the mutex is initialized).

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty multipath-tcp#250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 [<c010e0d8>] (unwind_backtrace) from [<c010beac>] (show_stack+0x10/0x14)
 [<c010beac>] (show_stack) from [<c017401c>] (register_lock_class+0x4f4/0x55c)
 [<c017401c>] (register_lock_class) from [<c0176fe0>] (__lock_acquire+0x74/0x1938)
 [<c0176fe0>] (__lock_acquire) from [<c0178cfc>] (lock_acquire+0xfc/0x23c)
 [<c0178cfc>] (lock_acquire) from [<c08aa2f8>] (mutex_lock_nested+0x50/0x3b0)
 [<c08aa2f8>] (mutex_lock_nested) from [<c05f5bf8>] (rtl8187_start+0x2c/0xd54)
 [<c05f5bf8>] (rtl8187_start) from [<c082dea0>] (drv_start+0xa8/0x320)
 [<c082dea0>] (drv_start) from [<c084d1d4>] (ieee80211_do_open+0x2bc/0x8e4)
 [<c084d1d4>] (ieee80211_do_open) from [<c069be94>] (__dev_open+0xb8/0x120)
 [<c069be94>] (__dev_open) from [<c069c11c>] (__dev_change_flags+0x88/0x14c)
 [<c069c11c>] (__dev_change_flags) from [<c069c1f8>] (dev_change_flags+0x18/0x48)
 [<c069c1f8>] (dev_change_flags) from [<c0710b08>] (devinet_ioctl+0x738/0x840)
 [<c0710b08>] (devinet_ioctl) from [<c067925c>] (sock_ioctl+0x164/0x2f4)
 [<c067925c>] (sock_ioctl) from [<c02883f8>] (do_vfs_ioctl+0x8c/0x9d0)
 [<c02883f8>] (do_vfs_ioctl) from [<c0288da8>] (SyS_ioctl+0x6c/0x7c)
 [<c0288da8>] (SyS_ioctl) from [<c0107760>] (ret_fast_syscall+0x0/0x1c)
 Unable to handle kernel NULL pointer dereference at virtual address 00000000
 pgd = cd1ec000
 [00000000] *pgd=8d1de831, *pte=00000000, *ppte=00000000
 Internal error: Oops: 817 [#1] PREEMPT ARM
 Modules linked in:
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty multipath-tcp#250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 task: ce73eec0 task.stack: cd1ea000
 PC is at mutex_lock_nested+0xe8/0x3b0
 LR is at mutex_lock_nested+0xd0/0x3b0

Cc: [email protected]
Signed-off-by: Sudhir Sreedharan <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
cpaasch pushed a commit that referenced this issue May 16, 2018
commit 7972326 upstream.

This can be reproduced by bind/unbind the driver multiple times
in AM3517 board.

Analysis revealed that rtl8187_start() was invoked before probe
finishes(ie. before the mutex is initialized).

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty #250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 [<c010e0d8>] (unwind_backtrace) from [<c010beac>] (show_stack+0x10/0x14)
 [<c010beac>] (show_stack) from [<c017401c>] (register_lock_class+0x4f4/0x55c)
 [<c017401c>] (register_lock_class) from [<c0176fe0>] (__lock_acquire+0x74/0x1938)
 [<c0176fe0>] (__lock_acquire) from [<c0178cfc>] (lock_acquire+0xfc/0x23c)
 [<c0178cfc>] (lock_acquire) from [<c08aa2f8>] (mutex_lock_nested+0x50/0x3b0)
 [<c08aa2f8>] (mutex_lock_nested) from [<c05f5bf8>] (rtl8187_start+0x2c/0xd54)
 [<c05f5bf8>] (rtl8187_start) from [<c082dea0>] (drv_start+0xa8/0x320)
 [<c082dea0>] (drv_start) from [<c084d1d4>] (ieee80211_do_open+0x2bc/0x8e4)
 [<c084d1d4>] (ieee80211_do_open) from [<c069be94>] (__dev_open+0xb8/0x120)
 [<c069be94>] (__dev_open) from [<c069c11c>] (__dev_change_flags+0x88/0x14c)
 [<c069c11c>] (__dev_change_flags) from [<c069c1f8>] (dev_change_flags+0x18/0x48)
 [<c069c1f8>] (dev_change_flags) from [<c0710b08>] (devinet_ioctl+0x738/0x840)
 [<c0710b08>] (devinet_ioctl) from [<c067925c>] (sock_ioctl+0x164/0x2f4)
 [<c067925c>] (sock_ioctl) from [<c02883f8>] (do_vfs_ioctl+0x8c/0x9d0)
 [<c02883f8>] (do_vfs_ioctl) from [<c0288da8>] (SyS_ioctl+0x6c/0x7c)
 [<c0288da8>] (SyS_ioctl) from [<c0107760>] (ret_fast_syscall+0x0/0x1c)
 Unable to handle kernel NULL pointer dereference at virtual address 00000000
 pgd = cd1ec000
 [00000000] *pgd=8d1de831, *pte=00000000, *ppte=00000000
 Internal error: Oops: 817 [#1] PREEMPT ARM
 Modules linked in:
 CPU: 0 PID: 821 Comm: wpa_supplicant Not tainted 4.9.80-dirty #250
 Hardware name: Generic AM3517 (Flattened Device Tree)
 task: ce73eec0 task.stack: cd1ea000
 PC is at mutex_lock_nested+0xe8/0x3b0
 LR is at mutex_lock_nested+0xd0/0x3b0

Cc: [email protected]
Signed-off-by: Sudhir Sreedharan <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
@teto
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teto commented Feb 8, 2019

If you are able to capture pcaps on both hosts, you can use https://github.com/teto/mptcpanalyzer to classify reinjections (between successful and failed) from the traces. Downside is you will need to compile wireshark yourself as the necessary patches haven't been released yet. Feel free to ping me or open an issue on the project repository if you have problems/qustions.

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