Re: Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)
On 02/27/2018 01:36 PM, Sebastian Andrzej Siewior wrote: On 2018-02-27 19:40:34 [+0100], Greg Kroah-Hartman wrote: On Tue, Feb 27, 2018 at 06:33:14PM +0100, Sebastian Andrzej Siewior wrote: On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote: That issue remains unclear to me: Are probes of PCI devices guaranteed to be serialized? Observations on my CCPs says that they occur in order, but I don't know for certain that serialization is guaranteed. Is there a definitive statement on this somewhere that I just don't know about? The bus enforces this. So the question if a driver can probe two devices simultaneously. Depends on the bus type. PCI So the question is whether or not PCI enforces serial activity within a domain. The CCPs are all on different buses, so that doesn't matter. I think we don't care in this situation, given that the CCP driver has minor requirements for locking. I just found it an interesting (albeit somewhat academic) question. Thanks, Gary
Re: Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)
On 2018-02-27 19:40:34 [+0100], Greg Kroah-Hartman wrote: > On Tue, Feb 27, 2018 at 06:33:14PM +0100, Sebastian Andrzej Siewior wrote: > > On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote: > > > That issue remains unclear to me: Are probes of PCI devices guaranteed to > > > be > > > serialized? Observations on my CCPs says that they occur in order, but I > > > don't know for certain that serialization is guaranteed. > > > > > > Is there a definitive statement on this somewhere that I just don't know > > > about? > > The bus enforces this. > > > So the question if a driver can probe two devices simultaneously. > > Depends on the bus type. PCI > thanks, > > greg k-h Sebastian
Re: Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)
On Tue, Feb 27, 2018 at 06:33:14PM +0100, Sebastian Andrzej Siewior wrote: > On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote: > > That issue remains unclear to me: Are probes of PCI devices guaranteed to be > > serialized? Observations on my CCPs says that they occur in order, but I > > don't know for certain that serialization is guaranteed. > > > > Is there a definitive statement on this somewhere that I just don't know > > about? The bus enforces this. > So the question if a driver can probe two devices simultaneously. Depends on the bus type. thanks, greg k-h
Re: Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)
On 02/27/2018 11:33 AM, Sebastian Andrzej Siewior wrote: On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote: That issue remains unclear to me: Are probes of PCI devices guaranteed to be serialized? Observations on my CCPs says that they occur in order, but I don't know for certain that serialization is guaranteed. Is there a definitive statement on this somewhere that I just don't know about? So the question if a driver can probe two devices simultaneously. I'm not sure. We have PROBE_PREFER_ASYNCHRONOUS which defers the probe to worker. However I have no idea if two of those worker can run at the same time. I think a mutex would be just fine; I got this wrong, clearly. Let me work up a patch using a mutex. I've sent one. Why not just ack it and be done with it? Gary Sebastian Sorry, too much chaos right now. Of course.
Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)
On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote: > That issue remains unclear to me: Are probes of PCI devices guaranteed to be > serialized? Observations on my CCPs says that they occur in order, but I > don't know for certain that serialization is guaranteed. > > Is there a definitive statement on this somewhere that I just don't know > about? So the question if a driver can probe two devices simultaneously. I'm not sure. We have PROBE_PREFER_ASYNCHRONOUS which defers the probe to worker. However I have no idea if two of those worker can run at the same time. > I think a mutex would be just fine; I got this wrong, clearly. Let me work > up a patch using a mutex. I've sent one. Why not just ack it and be done with it? > Gary Sebastian
