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DMAResource::TranslateNext(): Fixed several bugs that could cause too

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many bytes to be read/written, which, among other things, could trigger
an assert in the IORequest code:
* In case of a partial (i.e. non-block-aligned) begin, transferLeft was
  not adjusted correctly.
* The main loop was lacking a transferLeft check.
* Main loop: When finally using a bounce buffer, the unrestricted vec
  length was used as base length for the bounce buffer.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@27042 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2008-08-18 15:32:11 +00:00
parent 27a11ab8b0
commit ff388d5189
1 changed files with 16 additions and 7 deletions
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23
src/system/kernel/device_manager/dma_resources.cpp
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@ -483,13 +483,21 @@ DMAResource::TranslateNext(IORequest* request, IOOperation* operation)
dmaLength += length;
vecOffset += length - partialBegin;
size_t transferred = length - partialBegin;
vecOffset += transferred;
offset -= partialBegin;
if (transferLeft > transferred)
transferLeft -= transferred;
else
transferLeft = 0;
TRACE(" partial begin, using bounce buffer: offset: %lld, length: "
"%lu\n", offset, length);
}
for (uint32 i = vecIndex; i < vecIndex + segmentCount;) {
for (uint32 i = vecIndex;
i < vecIndex + segmentCount && transferLeft > 0;) {
if (dmaBuffer->VecCount() >= fRestrictions.max_segment_count)
break;
@ -501,9 +509,10 @@ DMAResource::TranslateNext(IORequest* request, IOOperation* operation)
}
addr_t base = (addr_t)vec.iov_base + vecOffset;
size_t length = vec.iov_len - vecOffset;
if (length > transferLeft)
length = transferLeft;
size_t maxLength = vec.iov_len - vecOffset;
if (maxLength > transferLeft)
maxLength = transferLeft;
size_t length = maxLength;
// Cut the vec according to transfer size, segment size, and boundary.
@ -540,7 +549,7 @@ DMAResource::TranslateNext(IORequest* request, IOOperation* operation)
// If length is 0, use bounce buffer for complete vec.
if (length == 0) {
length = vec.iov_len - vecOffset;
length = maxLength;
useBounceBufferSize = length;
TRACE(" vec %lu: 0 length, using bounce buffer: %lu\n", i,
useBounceBufferSize);
@ -567,7 +576,7 @@ DMAResource::TranslateNext(IORequest* request, IOOperation* operation)
dmaLength += length;
vecOffset += length;
transferLeft -= length;
transferLeft -= min_c(length, transferLeft);
}
// If we're writing partially, we always need to have a block sized bounce