Re: [ros-diffs] [hbirr] 14421: - Use IoBuildAsynchronousFsdRequest instead IoBuildSynchronousFsdRequest in NtRead/WriteFile.
4 Apr
2005
4 Apr
'05
9:55 p.m.
hbirr(a)svn.reactos.com wrote:
I dont understand these changes... Why did you change from sync. to
asycn. version, and whats the point with try/except around
IoBuildAsynchronousFsdRequest???
Gunnar
4 Apr
4 Apr
11:28 p.m.
New subject: [ros-diffs] [hbirr] 14421: - Use IoBuildAsynchronousFsdRequest instead IoBuildSynchronousFsdRequest in NtRead/WriteFile.
Gunnar Dalsnes wrote:
I've guarded the calls to IoBuildAsynchronousFsdRequest because
IoBuildAsynchronousFsdRequest calls MmProbeAndLockPages which can raise
an exception if the buffer isn't valid.
IoBuildSynchronousFsdRequest does always queue the irps to the threads
cancel/cleanup list. This isn't correct for asynchronous requests.
- Hartmut
11:56 p.m.
New subject: [ros-diffs] [hbirr] 14421: - Use IoBuildAsynchronousFsdRequest instead IoBuildSynchronousFsdRequest in NtRead/WriteFile.
IoBuildSynchronousFsdRequest does always queue the irps to the threads
cancel/cleanup list. This isn't correct for asynchronous requests.
Hehe, this is a know misunderstanding:
The Synchronous/Asynchronous in IoBuildXxx refers to wheter the thread
context is non-arbitrary(synch) or arbitrary(asynch)! Yes, really! I can
only blame microsoft for makin such bad names:-D
A syscall is always in a non-arbitrary thread context thus it should
always use IoBuildSynchronousFsdRequest (or should it? see my other post).
Gunnar
11:35 p.m.
New subject: [ros-diffs] [hbirr] 14421: - Use IoBuildAsynchronousFsdRequest instead IoBuildSynchronousFsdRequest in NtRead/WriteFile.
I googled and found some stuff:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q326315
//
// If the target device object is set up do direct i/o (DO_DIRECT_IO), then
// IoBuildAsynchronousFsdRequest creates an MDL to describe the buffer
// and locks the pages.
We also probe and lock, so it seems ros IoBuildAsynchronousFsdRequest is
correct at this point. But the docs says nothing about
IoBuildAsynchronousFsdRequest throwing an exception, and i have never
seen any code guarding a call to IoBuildAsynchronousFsdRequest either...
googled some more:
http://drucifer.shackspace.com/bsod.txt
DRIVER_VERIFIER_IOMANAGER_VIOLATION (0xC9)
8. Call to IoBuildAsynchronousFsdRequest threw an exception
2 - the Device object
3 - the IRP major function
4 - the exception status
Hmm. So it seems IoBuildAsynchronousFsdRequest CAN throw and exception
but is not allowed to do so, even thou it uses MmProbeAndLockPages! Imo,
this can only mean that its not allowed to use
IoBuildAsynchronousFsdRequest/IoBuildSynchronousFsdRequest with umode
buffers! (MmProbeAndLockPages with kmode buffer will never fail)
Gunnar
Gunnar Dalsnes wrote:
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days inactive
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3 comments
2 participants
participants (2)
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Gunnar Dalsnes -
Hartmut Birr