linux-kernel - RE: [PATCH 1/2] staging: hv: Fix race condition in hv

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Message-ID: <1FB5E1D5CA062146B38059374562DF7266B894B0@TK5EX14MBXC128.redmond.corp.microsoft.com>
Date:	Wed, 19 May 2010 20:30:25 +0000
From:	Haiyang Zhang <haiyangz@...rosoft.com>
To:	Greg KH <gregkh@...e.de>
CC:	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'devel@...verdev.osuosl.org'" <devel@...verdev.osuosl.org>,
	"'virtualization@...ts.osdl.org'" <virtualization@...ts.osdl.org>,
	"Hank Janssen" <hjanssen@...rosoft.com>
Subject: RE: [PATCH 1/2] staging: hv: Fix race condition in hv_utils module
 initialization.

> > +	/* Wait until all IC channels are initialized */
> > +	while (atomic_read(&hv_utils_initcnt) < MAX_MSG_TYPES)
> > +		msleep(100);
> 
> No, don't do this here, do something in your hv_vmbus core to handle
> registering sub-drivers properly.  Perhaps you need to sleep there
> before you can succeed on a initialization.

Thanks for the recommendation. I will put the sleep into vmbus_init to 
ensure all channels are ready before the vmbus_init function exits.

> >  	hv_cb_utils[HV_SHUTDOWN_MSG].channel->OnChannelCallback =
> >  		&shutdown_onchannelcallback;
> 
> The problem is that you just have a bunch of callbacks you are setting
> up, it's not a "real" function call.  Please change it over to a
> function call, like all other subsystems have.  Then, you can handle
> any
> "sleep until we are set up properly" issues in the vmbus code, not in
> each and every individual bus driver.

Actually, we already assign a default callback function, chn_cb_negotiate(),
when the channels are opened in vmbus module. It's a real function and can 
handle common negotiation messages.
I will move the sleep into vmbus module as well.

Thanks,

- Haiyang
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