From: David Miller <davem@davemloft.net>
To: decui@microsoft.com
Cc: gregkh@linuxfoundation.org, stephen@networkplumber.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
driverdev-devel@linuxdriverproject.org, olaf@aepfle.de,
apw@canonical.com, jasowang@redhat.com, kys@microsoft.com,
pebolle@tiscali.nl, stefanha@redhat.com, vkuznets@redhat.com,
dan.carpenter@oracle.com
Subject: Re: [PATCH V4 7/7] Drivers: hv: vmbus: disable local interrupt when hvsock's callback is running
Date: Wed, 29 Jul 2015 15:28:09 -0700 (PDT) [thread overview]
Message-ID: <20150729.152809.1531386671239230150.davem@davemloft.net> (raw)
In-Reply-To: <1438086930-19483-1-git-send-email-decui@microsoft.com>
From: Dexuan Cui <decui@microsoft.com>
Date: Tue, 28 Jul 2015 05:35:30 -0700
> In the SMP guest case, when the per-channel callback hvsock_events() is
> running on virtual CPU A, if the guest tries to close the connection on
> virtual CPU B: we invoke vmbus_close() -> vmbus_close_internal(),
> then we can have trouble: on B, vmbus_close_internal() will send IPI
> reset_channel_cb() to A, trying to set channel->onchannel_callbackto NULL;
> on A, if the IPI handler happens between
> "if (channel->onchannel_callback != NULL)" and invoking
> channel->onchannel_callback, we'll invoke a function pointer of NULL.
>
> This is why the patch is necessary.
>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
Sorry, I do not accept that you must use conditional locking and/or
IRQ disabling.
Boil it down to what is necessary for the least common denominator,
and use that unconditionally.
next prev parent reply other threads:[~2015-07-29 22:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 12:35 Dexuan Cui
2015-07-29 22:28 ` David Miller [this message]
2015-07-30 10:18 ` Dexuan Cui
2015-08-06 4:44 ` Dexuan Cui
2015-08-06 17:50 ` KY Srinivasan
2015-08-07 10:24 ` Dexuan Cui
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