<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/usb/mon/mon_text.c, branch v3.2.68</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>usb: Add export.h for EXPORT_SYMBOL/THIS_MODULE where needed</title>
<updated>2011-10-31T23:31:25+00:00</updated>
<author>
<name>Paul Gortmaker</name>
<email>paul.gortmaker@windriver.com</email>
</author>
<published>2011-05-27T13:56:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f940fcd8eadfe5b909a1474b57de7755edeee62b'/>
<id>f940fcd8eadfe5b909a1474b57de7755edeee62b</id>
<content type='text'>
With module.h being implicitly everywhere via device.h, the absence
of explicitly including something for EXPORT_SYMBOL went unnoticed.
Since we are heading to fix things up and clean module.h from the
device.h file, we need to explicitly include these files now.

Use the lightweight version of the header that has just THIS_MODULE
and EXPORT_SYMBOL variants.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
With module.h being implicitly everywhere via device.h, the absence
of explicitly including something for EXPORT_SYMBOL went unnoticed.
Since we are heading to fix things up and clean module.h from the
device.h file, we need to explicitly include these files now.

Use the lightweight version of the header that has just THIS_MODULE
and EXPORT_SYMBOL variants.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>USB: mon: Allow to use usbmon without debugfs</title>
<updated>2011-07-08T21:55:09+00:00</updated>
<author>
<name>Tobias Klauser</name>
<email>tklauser@distanz.ch</email>
</author>
<published>2011-07-07T07:28:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8dec92b24064f1ffbb6537ba97729b633b400c28'/>
<id>8dec92b24064f1ffbb6537ba97729b633b400c28</id>
<content type='text'>
Do not bail out with an error in mon_text_init() if debugfs is not
available, instead just return 0 and let mon_init() go ahead with
loading the binary API. Return -ENOMEM in case debugfs_create_dir()
fails for other reasons. Later, it is enough to check for mon_dir
not set.

Signed-off-by: Tobias Klauser &lt;tklauser@distanz.ch&gt;
Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Do not bail out with an error in mon_text_init() if debugfs is not
available, instead just return 0 and let mon_init() go ahead with
loading the binary API. Return -ENOMEM in case debugfs_create_dir()
fails for other reasons. Later, it is enough to check for mon_dir
not set.

Signed-off-by: Tobias Klauser &lt;tklauser@distanz.ch&gt;
Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>USB: usbmon: fix-up docs and text API for sparse ISO</title>
<updated>2011-02-04T19:46:57+00:00</updated>
<author>
<name>Pete Zaitcev</name>
<email>zaitcev@redhat.com</email>
</author>
<published>2011-02-04T05:01:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d25bc4db723a44c097268b466ff74bfba4bcc4f3'/>
<id>d25bc4db723a44c097268b466ff74bfba4bcc4f3</id>
<content type='text'>
This is based on a patch that Alan Stern wrote. It did the same simple
thing in both text and binary cases. In the same time, Marton and I
fixed the binary side properly, but this leaves the text to be fixed.
It is not very important due to low maxium data size of text, but
let's add it just for extra correctness.

The pseudocode is too much to keep fixed up, and we have real code
to be used as examples now, so let's drop it too.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is based on a patch that Alan Stern wrote. It did the same simple
thing in both text and binary cases. In the same time, Marton and I
fixed the binary side properly, but this leaves the text to be fixed.
It is not very important due to low maxium data size of text, but
let's add it just for extra correctness.

The pseudocode is too much to keep fixed up, and we have real code
to be used as examples now, so let's drop it too.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>USB: Change the scatterlist type in struct urb</title>
<updated>2010-05-20T20:21:41+00:00</updated>
<author>
<name>Matthew Wilcox</name>
<email>matthew@wil.cx</email>
</author>
<published>2010-05-01T18:20:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=910f8d0cede74beff1eee93cf9cf2a28d7600e66'/>
<id>910f8d0cede74beff1eee93cf9cf2a28d7600e66</id>
<content type='text'>
Change the type of the URB's 'sg' pointer from a usb_sg_request to
a scatterlist.  This allows drivers to submit scatter-gather lists
without using the usb_sg_wait() interface.  It has the added benefit
of removing the typecasts that were added as part of patch as1368 (and
slightly decreasing the number of pointer dereferences).

Signed-off-by: Matthew Wilcox &lt;willy@linux.intel.com&gt;
Reviewed-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Tested-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Change the type of the URB's 'sg' pointer from a usb_sg_request to
a scatterlist.  This allows drivers to submit scatter-gather lists
without using the usb_sg_wait() interface.  It has the added benefit
of removing the typecasts that were added as part of patch as1368 (and
slightly decreasing the number of pointer dereferences).

Signed-off-by: Matthew Wilcox &lt;willy@linux.intel.com&gt;
Reviewed-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Tested-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>USB: fix usbmon and DMA mapping for scatter-gather URBs</title>
<updated>2010-05-20T20:21:37+00:00</updated>
<author>
<name>Alan Stern</name>
<email>stern@rowland.harvard.edu</email>
</author>
<published>2010-04-02T17:27:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ff9c895f07d36193c75533bda8193bde8ca99d02'/>
<id>ff9c895f07d36193c75533bda8193bde8ca99d02</id>
<content type='text'>
This patch (as1368) fixes a rather obscure bug in usbmon: When tracing
URBs sent by the scatter-gather library, it accesses the data buffers
while they are still mapped for DMA.

The solution is to move the mapping and unmapping out of the s-g
library and into the usual place in hcd.c.  This requires the addition
of new URB flag bits to describe the kind of mapping needed, since we
have to call dma_map_sg() if the HCD supports native scatter-gather
operation and dma_map_page() if it doesn't.  The nice thing about
having the new flags is that they simplify the testing for unmapping.

The patch removes the only caller of usb_buffer_[un]map_sg(), so those
functions are #if'ed out.  A later patch will remove them entirely.

As a result of this change, urb-&gt;sg will be set in situations where
it wasn't set previously.  Hence the xhci and whci drivers are
adjusted to test urb-&gt;num_sgs instead, which retains its original
meaning and is nonzero only when the HCD has to handle a scatterlist.

Finally, even when a submission error occurs we don't want to hand
URBs to usbmon before they are unmapped.  The submission path is
rearranged so that map_urb_for_dma() is called only for non-root-hub
URBs and unmap_urb_for_dma() is called immediately after a submission
error.  This simplifies the error handling.

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
CC: &lt;stable@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch (as1368) fixes a rather obscure bug in usbmon: When tracing
URBs sent by the scatter-gather library, it accesses the data buffers
while they are still mapped for DMA.

The solution is to move the mapping and unmapping out of the s-g
library and into the usual place in hcd.c.  This requires the addition
of new URB flag bits to describe the kind of mapping needed, since we
have to call dma_map_sg() if the HCD supports native scatter-gather
operation and dma_map_page() if it doesn't.  The nice thing about
having the new flags is that they simplify the testing for unmapping.

The patch removes the only caller of usb_buffer_[un]map_sg(), so those
functions are #if'ed out.  A later patch will remove them entirely.

As a result of this change, urb-&gt;sg will be set in situations where
it wasn't set previously.  Hence the xhci and whci drivers are
adjusted to test urb-&gt;num_sgs instead, which retains its original
meaning and is nonzero only when the HCD has to handle a scatterlist.

Finally, even when a submission error occurs we don't want to hand
URBs to usbmon before they are unmapped.  The submission path is
rearranged so that map_urb_for_dma() is called only for non-root-hub
URBs and unmap_urb_for_dma() is called immediately after a submission
error.  This simplifies the error handling.

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
CC: &lt;stable@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</pre>
</div>
</content>
</entry>
<entry>
<title>include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h</title>
<updated>2010-03-30T13:02:32+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2010-03-24T08:04:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5a0e3ad6af8660be21ca98a971cd00f331318c05'/>
<id>5a0e3ad6af8660be21ca98a971cd00f331318c05</id>
<content type='text'>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -&gt; slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Guess-its-ok-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Lee Schermerhorn &lt;Lee.Schermerhorn@hp.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -&gt; slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Guess-its-ok-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Lee Schermerhorn &lt;Lee.Schermerhorn@hp.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>USB: usbmon: mask seconds properly in text API</title>
<updated>2010-03-02T22:55:14+00:00</updated>
<author>
<name>Pete Zaitcev</name>
<email>zaitcev@redhat.com</email>
</author>
<published>2010-02-20T06:55:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=47cb17089c059d24e5da03f2b44ee3a089075b78'/>
<id>47cb17089c059d24e5da03f2b44ee3a089075b78</id>
<content type='text'>
The code does not implement the comment, so timestamps for long traces
become confusing instead of wrapping neatly as expected. This was actually
observed. Fortunately for API being in debugfs, we can just fix this instead
of staying bug-for-bug compatible. Double fortunately, the stable binary
API is not affected.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The code does not implement the comment, so timestamps for long traces
become confusing instead of wrapping neatly as expected. This was actually
observed. Fortunately for API being in debugfs, we can just fix this instead
of staying bug-for-bug compatible. Double fortunately, the stable binary
API is not affected.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</pre>
</div>
</content>
</entry>
<entry>
<title>usbmon: add bus number to text API</title>
<updated>2010-03-02T22:53:30+00:00</updated>
<author>
<name>Pete Zaitcev</name>
<email>zaitcev@redhat.com</email>
</author>
<published>2010-01-05T18:50:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2bc0d109326e9f2b25fa1dfcc9de2489e1e00e36'/>
<id>2bc0d109326e9f2b25fa1dfcc9de2489e1e00e36</id>
<content type='text'>
Due to a simple oversight when bus zero was added, the text API fails to
deliver the bus number in 'E' messages (which are equivalent of 'C'
messages, only for error case). This makes it harder, for instance,
use a search-and-highlight in a text editor. So fix it.

Also, Alan Stern requested adding timestamps to 'E' messages. This is
purely cosmetic, but makes it easier to read the trace. This is done
for both text and binary APIs.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Due to a simple oversight when bus zero was added, the text API fails to
deliver the bus number in 'E' messages (which are equivalent of 'C'
messages, only for error case). This makes it harder, for instance,
use a search-and-highlight in a text editor. So fix it.

Also, Alan Stern requested adding timestamps to 'E' messages. This is
purely cosmetic, but makes it easier to read the trace. This is done
for both text and binary APIs.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;


</pre>
</div>
</content>
</entry>
<entry>
<title>USB: add scatter-gather support to usbmon</title>
<updated>2009-12-11T19:55:20+00:00</updated>
<author>
<name>Alan Stern</name>
<email>stern@rowland.harvard.edu</email>
</author>
<published>2009-11-06T17:32:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b375e1169d8ecc9e9db3ecba8147d484b5510833'/>
<id>b375e1169d8ecc9e9db3ecba8147d484b5510833</id>
<content type='text'>
This patch (as1301) adds support to usbmon for scatter-gather URBs.
The text interface looks at only the first scatterlist element, since
it never copies more than 32 bytes of data anyway.  The binary
interface copies as much data as possible up to the first
non-addressable buffer.

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
CC: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch (as1301) adds support to usbmon for scatter-gather URBs.
The text interface looks at only the first scatterlist element, since
it never copies more than 32 bytes of data anyway.  The binary
interface copies as much data as possible up to the first
non-addressable buffer.

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
CC: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>USB: usbmon: end ugly tricks with DMA peeking</title>
<updated>2009-09-23T13:46:19+00:00</updated>
<author>
<name>Pete Zaitcev</name>
<email>zaitcev@redhat.com</email>
</author>
<published>2009-06-11T14:53:20+00:00</published>
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This patch fixes crashes when usbmon attempts to access GART aperture.
The old code attempted to take a bus address and convert it into a
virtual address, which clearly was impossible on systems with actual
IOMMUs. Let us not persist in this foolishness, and use transfer_buffer
in all cases instead.

I think downsides are negligible. The ones I see are:
 - A driver may pass an address of one buffer down as transfer_buffer,
   and entirely different entity mapped for DMA, resulting in misleading
   output of usbmon. Note, however, that PIO based controllers would
   do transfer the same data that usbmon sees here.
 - Out of tree drivers may crash usbmon if they store garbage in
   transfer_buffer. I inspected the in-tree drivers, and clarified
   the documentation in comments.
 - Drivers that use get_user_pages will not be possible to monitor.
   I only found one driver with this problem (drivers/staging/rspiusb).
 - Same happens with with usb_storage transferring from highmem, but
   it works fine on 64-bit systems, so I think it's not a concern.
   At least we don't crash anymore.

Why didn't we do this in 2.6.10? That's because back in those days
it was popular not to fill in transfer_buffer, so almost all
traffic would be invisible (e.g. all of HID was like that).
But now, the tree is almost 100% PIO friendly, so we can do the
right thing at last.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

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<pre>
This patch fixes crashes when usbmon attempts to access GART aperture.
The old code attempted to take a bus address and convert it into a
virtual address, which clearly was impossible on systems with actual
IOMMUs. Let us not persist in this foolishness, and use transfer_buffer
in all cases instead.

I think downsides are negligible. The ones I see are:
 - A driver may pass an address of one buffer down as transfer_buffer,
   and entirely different entity mapped for DMA, resulting in misleading
   output of usbmon. Note, however, that PIO based controllers would
   do transfer the same data that usbmon sees here.
 - Out of tree drivers may crash usbmon if they store garbage in
   transfer_buffer. I inspected the in-tree drivers, and clarified
   the documentation in comments.
 - Drivers that use get_user_pages will not be possible to monitor.
   I only found one driver with this problem (drivers/staging/rspiusb).
 - Same happens with with usb_storage transferring from highmem, but
   it works fine on 64-bit systems, so I think it's not a concern.
   At least we don't crash anymore.

Why didn't we do this in 2.6.10? That's because back in those days
it was popular not to fill in transfer_buffer, so almost all
traffic would be invisible (e.g. all of HID was like that).
But now, the tree is almost 100% PIO friendly, so we can do the
right thing at last.

Signed-off-by: Pete Zaitcev &lt;zaitcev@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

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