Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
On 9/16/19 4:00 AM, Kevin Wolf wrote: > Am 13.09.2019 um 20:49 hat John Snow geschrieben: >> On 9/12/19 4:20 AM, Vladimir Sementsov-Ogievskiy wrote: >>> Also, I'm not sure about "are" suggested by Max. "are" is for plural, but >>> here I meant >>> one object: sum of @start and @count. >>> >> >> There's not great agreement universally about how to treat things like >> collective nouns. Sometimes "Data" is singular, but sometimes it's >> plural. "It depends." >> >> In this case, "start + count" refers to one sum, but two constituent >> pieces, so it's functioning like a collective noun. >> >> We might say "a + b (together) /are/ ..." but also "the sum of a + b /is/". >> >>> So, you may use exactly "Sum of @start and @count is" or "(@start + @count) >>> sum is" or >>> just "(@start + @count) is", whichever you like more. >>> >> >> I like using "the sum of @x and @y is" for being grammatically unambiguous. >> >> updated and pushed. >> >> (Sorry about my language again! --js) > > Time to revive https://patchwork.kernel.org/patch/8725621/? ;-) > > Kevin > Ja, bitte.
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
Am 13.09.2019 um 20:49 hat John Snow geschrieben: > On 9/12/19 4:20 AM, Vladimir Sementsov-Ogievskiy wrote: > > Also, I'm not sure about "are" suggested by Max. "are" is for plural, but > > here I meant > > one object: sum of @start and @count. > > > > There's not great agreement universally about how to treat things like > collective nouns. Sometimes "Data" is singular, but sometimes it's > plural. "It depends." > > In this case, "start + count" refers to one sum, but two constituent > pieces, so it's functioning like a collective noun. > > We might say "a + b (together) /are/ ..." but also "the sum of a + b /is/". > > > So, you may use exactly "Sum of @start and @count is" or "(@start + @count) > > sum is" or > > just "(@start + @count) is", whichever you like more. > > > > I like using "the sum of @x and @y is" for being grammatically unambiguous. > > updated and pushed. > > (Sorry about my language again! --js) Time to revive https://patchwork.kernel.org/patch/8725621/? ;-) Kevin
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
On 9/12/19 4:20 AM, Vladimir Sementsov-Ogievskiy wrote: > 11.09.2019 20:59, John Snow wrote: >> >> >> On 9/11/19 11:13 AM, Vladimir Sementsov-Ogievskiy wrote: >>> 07.08.2019 19:27, John Snow wrote: On 8/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote: > 06.08.2019 19:09, Max Reitz wrote: >> On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: >>> hbitmap_reset has an unobvious property: it rounds requested region up. >>> It may provoke bugs, like in recently fixed write-blocking mode of >>> mirror: user calls reset on unaligned region, not keeping in mind that >>> there are possible unrelated dirty bytes, covered by rounded-up region >>> and information of this unrelated "dirtiness" will be lost. >>> >>> Make hbitmap_reset strict: assert that arguments are aligned, allowing >>> only one exception when @start + @count == hb->orig_size. It's needed >>> to comfort users of hbitmap_next_dirty_area, which cares about >>> hb->orig_size. >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> --- >>> >>> v2 based on Max's https://github.com/XanClic/qemu.git block >>> which will be merged soon to 4.1, and this patch goes to 4.2 >>> Based-on: https://github.com/XanClic/qemu.git block >>> >>> v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand >>> we all agreed to just assert alignment instead of aligning down >>> automatically. >>> >>> include/qemu/hbitmap.h | 5 + >>> tests/test-hbitmap.c | 2 +- >>> util/hbitmap.c | 4 >>> 3 files changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >>> index 4afbe6292e..7865e819ca 100644 >>> --- a/include/qemu/hbitmap.h >>> +++ b/include/qemu/hbitmap.h >>> @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, >>> uint64_t count); >>> * @count: Number of bits to reset. >>> * >>> * Reset a consecutive range of bits in an HBitmap. >>> + * @start and @count must be aligned to bitmap granularity. The only >>> exception >>> + * is resetting the tail of the bitmap: @count may be equal to @start + >>> + * hb->orig_size, >> >> s/@start + hb->orig_size/hb->orig_size - @start/, I think. > > Ha, I wanted to say start + count equal to orig_size. Yours is OK too of > course. > >> >>>in this case @count may be not aligned. @start + @count >> >> +are >> >> With those fixed: >> >> Reviewed-by: Max Reitz > > Thanks! > I'll add this to the pile for 4.2, after I fix the rebase conflicts that arose from 4.1-rc4. >>> >>> Hi! >>> >>> Didn't you forget, or should I resend? >>> >>> >> >> I must have dropped the patch by accident during the rebasing. As an >> apology, I squashed in Max's suggestions from the list. Check that they >> look OK, please? >> >> Thanks, applied to my bitmaps tree: >> >> https://github.com/jnsnow/qemu/commits/bitmaps >> https://github.com/jnsnow/qemu.git >> > > Thanks! Still: > > Quote from your branch: > > > * Reset a consecutive range of bits in an HBitmap. > > + * @start and @count must be aligned to bitmap granularity. The only > exception > > + * is resetting the tail of the bitmap: @count may be equal to > hb->orig_size - > > + * start, in this case @count may be not aligned. @start + @count are > > s/start/@start/ (corresponds to Max's comment, too) > OK, you got it. > Also, I'm not sure about "are" suggested by Max. "are" is for plural, but > here I meant > one object: sum of @start and @count. > There's not great agreement universally about how to treat things like collective nouns. Sometimes "Data" is singular, but sometimes it's plural. "It depends." In this case, "start + count" refers to one sum, but two constituent pieces, so it's functioning like a collective noun. We might say "a + b (together) /are/ ..." but also "the sum of a + b /is/". > So, you may use exactly "Sum of @start and @count is" or "(@start + @count) > sum is" or > just "(@start + @count) is", whichever you like more. > I like using "the sum of @x and @y is" for being grammatically unambiguous. updated and pushed. (Sorry about my language again! --js)
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
11.09.2019 20:59, John Snow wrote: > > > On 9/11/19 11:13 AM, Vladimir Sementsov-Ogievskiy wrote: >> 07.08.2019 19:27, John Snow wrote: >>> >>> >>> On 8/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote: 06.08.2019 19:09, Max Reitz wrote: > On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: >> hbitmap_reset has an unobvious property: it rounds requested region up. >> It may provoke bugs, like in recently fixed write-blocking mode of >> mirror: user calls reset on unaligned region, not keeping in mind that >> there are possible unrelated dirty bytes, covered by rounded-up region >> and information of this unrelated "dirtiness" will be lost. >> >> Make hbitmap_reset strict: assert that arguments are aligned, allowing >> only one exception when @start + @count == hb->orig_size. It's needed >> to comfort users of hbitmap_next_dirty_area, which cares about >> hb->orig_size. >> >> Signed-off-by: Vladimir Sementsov-Ogievskiy >> --- >> >> v2 based on Max's https://github.com/XanClic/qemu.git block >> which will be merged soon to 4.1, and this patch goes to 4.2 >> Based-on: https://github.com/XanClic/qemu.git block >> >> v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand >> we all agreed to just assert alignment instead of aligning down >> automatically. >> >> include/qemu/hbitmap.h | 5 + >> tests/test-hbitmap.c | 2 +- >> util/hbitmap.c | 4 >> 3 files changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >> index 4afbe6292e..7865e819ca 100644 >> --- a/include/qemu/hbitmap.h >> +++ b/include/qemu/hbitmap.h >> @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, >> uint64_t count); >> * @count: Number of bits to reset. >> * >> * Reset a consecutive range of bits in an HBitmap. >> + * @start and @count must be aligned to bitmap granularity. The only >> exception >> + * is resetting the tail of the bitmap: @count may be equal to @start + >> + * hb->orig_size, > > s/@start + hb->orig_size/hb->orig_size - @start/, I think. Ha, I wanted to say start + count equal to orig_size. Yours is OK too of course. > >>in this case @count may be not aligned. @start + @count > > +are > > With those fixed: > > Reviewed-by: Max Reitz Thanks! >>> >>> I'll add this to the pile for 4.2, after I fix the rebase conflicts that >>> arose from 4.1-rc4. >>> >> >> Hi! >> >> Didn't you forget, or should I resend? >> >> > > I must have dropped the patch by accident during the rebasing. As an > apology, I squashed in Max's suggestions from the list. Check that they > look OK, please? > > Thanks, applied to my bitmaps tree: > > https://github.com/jnsnow/qemu/commits/bitmaps > https://github.com/jnsnow/qemu.git > Thanks! Still: Quote from your branch: > * Reset a consecutive range of bits in an HBitmap. > + * @start and @count must be aligned to bitmap granularity. The only > exception > + * is resetting the tail of the bitmap: @count may be equal to > hb->orig_size - > + * start, in this case @count may be not aligned. @start + @count are s/start/@start/ (corresponds to Max's comment, too) Also, I'm not sure about "are" suggested by Max. "are" is for plural, but here I meant one object: sum of @start and @count. So, you may use exactly "Sum of @start and @count is" or "(@start + @count) sum is" or just "(@start + @count) is", whichever you like more. > + * allowed to be greater than hb->orig_size, but only if @start < > hb->orig_size > + * and @start + @count = ALIGN_UP(hb->orig_size, granularity). > */ > void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count); -- Best regards, Vladimir
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
On 9/11/19 11:13 AM, Vladimir Sementsov-Ogievskiy wrote: > 07.08.2019 19:27, John Snow wrote: >> >> >> On 8/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote: >>> 06.08.2019 19:09, Max Reitz wrote: On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: > hbitmap_reset has an unobvious property: it rounds requested region up. > It may provoke bugs, like in recently fixed write-blocking mode of > mirror: user calls reset on unaligned region, not keeping in mind that > there are possible unrelated dirty bytes, covered by rounded-up region > and information of this unrelated "dirtiness" will be lost. > > Make hbitmap_reset strict: assert that arguments are aligned, allowing > only one exception when @start + @count == hb->orig_size. It's needed > to comfort users of hbitmap_next_dirty_area, which cares about > hb->orig_size. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > > v2 based on Max's https://github.com/XanClic/qemu.git block > which will be merged soon to 4.1, and this patch goes to 4.2 > Based-on: https://github.com/XanClic/qemu.git block > > v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand > we all agreed to just assert alignment instead of aligning down > automatically. > >include/qemu/hbitmap.h | 5 + >tests/test-hbitmap.c | 2 +- >util/hbitmap.c | 4 >3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h > index 4afbe6292e..7865e819ca 100644 > --- a/include/qemu/hbitmap.h > +++ b/include/qemu/hbitmap.h > @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, > uint64_t count); > * @count: Number of bits to reset. > * > * Reset a consecutive range of bits in an HBitmap. > + * @start and @count must be aligned to bitmap granularity. The only > exception > + * is resetting the tail of the bitmap: @count may be equal to @start + > + * hb->orig_size, s/@start + hb->orig_size/hb->orig_size - @start/, I think. >>> >>> Ha, I wanted to say start + count equal to orig_size. Yours is OK too of >>> course. >>> > in this case @count may be not aligned. @start + @count +are With those fixed: Reviewed-by: Max Reitz >>> >>> Thanks! >>> >> >> I'll add this to the pile for 4.2, after I fix the rebase conflicts that >> arose from 4.1-rc4. >> > > Hi! > > Didn't you forget, or should I resend? > > I must have dropped the patch by accident during the rebasing. As an apology, I squashed in Max's suggestions from the list. Check that they look OK, please? Thanks, applied to my bitmaps tree: https://github.com/jnsnow/qemu/commits/bitmaps https://github.com/jnsnow/qemu.git --js
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
07.08.2019 19:27, John Snow wrote: > > > On 8/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote: >> 06.08.2019 19:09, Max Reitz wrote: >>> On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: hbitmap_reset has an unobvious property: it rounds requested region up. It may provoke bugs, like in recently fixed write-blocking mode of mirror: user calls reset on unaligned region, not keeping in mind that there are possible unrelated dirty bytes, covered by rounded-up region and information of this unrelated "dirtiness" will be lost. Make hbitmap_reset strict: assert that arguments are aligned, allowing only one exception when @start + @count == hb->orig_size. It's needed to comfort users of hbitmap_next_dirty_area, which cares about hb->orig_size. Signed-off-by: Vladimir Sementsov-Ogievskiy --- v2 based on Max's https://github.com/XanClic/qemu.git block which will be merged soon to 4.1, and this patch goes to 4.2 Based-on: https://github.com/XanClic/qemu.git block v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand we all agreed to just assert alignment instead of aligning down automatically. include/qemu/hbitmap.h | 5 + tests/test-hbitmap.c | 2 +- util/hbitmap.c | 4 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h index 4afbe6292e..7865e819ca 100644 --- a/include/qemu/hbitmap.h +++ b/include/qemu/hbitmap.h @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count); * @count: Number of bits to reset. * * Reset a consecutive range of bits in an HBitmap. + * @start and @count must be aligned to bitmap granularity. The only exception + * is resetting the tail of the bitmap: @count may be equal to @start + + * hb->orig_size, >>> >>> s/@start + hb->orig_size/hb->orig_size - @start/, I think. >> >> Ha, I wanted to say start + count equal to orig_size. Yours is OK too of >> course. >> >>> in this case @count may be not aligned. @start + @count >>> >>> +are >>> >>> With those fixed: >>> >>> Reviewed-by: Max Reitz >> >> Thanks! >> > > I'll add this to the pile for 4.2, after I fix the rebase conflicts that > arose from 4.1-rc4. > Hi! Didn't you forget, or should I resend? -- Best regards, Vladimir
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
On 8/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote: > 06.08.2019 19:09, Max Reitz wrote: >> On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: >>> hbitmap_reset has an unobvious property: it rounds requested region up. >>> It may provoke bugs, like in recently fixed write-blocking mode of >>> mirror: user calls reset on unaligned region, not keeping in mind that >>> there are possible unrelated dirty bytes, covered by rounded-up region >>> and information of this unrelated "dirtiness" will be lost. >>> >>> Make hbitmap_reset strict: assert that arguments are aligned, allowing >>> only one exception when @start + @count == hb->orig_size. It's needed >>> to comfort users of hbitmap_next_dirty_area, which cares about >>> hb->orig_size. >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> --- >>> >>> v2 based on Max's https://github.com/XanClic/qemu.git block >>> which will be merged soon to 4.1, and this patch goes to 4.2 >>> Based-on: https://github.com/XanClic/qemu.git block >>> >>> v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand >>> we all agreed to just assert alignment instead of aligning down >>> automatically. >>> >>> include/qemu/hbitmap.h | 5 + >>> tests/test-hbitmap.c | 2 +- >>> util/hbitmap.c | 4 >>> 3 files changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >>> index 4afbe6292e..7865e819ca 100644 >>> --- a/include/qemu/hbitmap.h >>> +++ b/include/qemu/hbitmap.h >>> @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t >>> count); >>>* @count: Number of bits to reset. >>>* >>>* Reset a consecutive range of bits in an HBitmap. >>> + * @start and @count must be aligned to bitmap granularity. The only >>> exception >>> + * is resetting the tail of the bitmap: @count may be equal to @start + >>> + * hb->orig_size, >> >> s/@start + hb->orig_size/hb->orig_size - @start/, I think. > > Ha, I wanted to say start + count equal to orig_size. Yours is OK too of > course. > >> >>> in this case @count may be not aligned. @start + @count >> >> +are >> >> With those fixed: >> >> Reviewed-by: Max Reitz > > Thanks! > I'll add this to the pile for 4.2, after I fix the rebase conflicts that arose from 4.1-rc4. --js
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
06.08.2019 19:09, Max Reitz wrote: > On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: >> hbitmap_reset has an unobvious property: it rounds requested region up. >> It may provoke bugs, like in recently fixed write-blocking mode of >> mirror: user calls reset on unaligned region, not keeping in mind that >> there are possible unrelated dirty bytes, covered by rounded-up region >> and information of this unrelated "dirtiness" will be lost. >> >> Make hbitmap_reset strict: assert that arguments are aligned, allowing >> only one exception when @start + @count == hb->orig_size. It's needed >> to comfort users of hbitmap_next_dirty_area, which cares about >> hb->orig_size. >> >> Signed-off-by: Vladimir Sementsov-Ogievskiy >> --- >> >> v2 based on Max's https://github.com/XanClic/qemu.git block >> which will be merged soon to 4.1, and this patch goes to 4.2 >> Based-on: https://github.com/XanClic/qemu.git block >> >> v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand >> we all agreed to just assert alignment instead of aligning down >> automatically. >> >> include/qemu/hbitmap.h | 5 + >> tests/test-hbitmap.c | 2 +- >> util/hbitmap.c | 4 >> 3 files changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >> index 4afbe6292e..7865e819ca 100644 >> --- a/include/qemu/hbitmap.h >> +++ b/include/qemu/hbitmap.h >> @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t >> count); >>* @count: Number of bits to reset. >>* >>* Reset a consecutive range of bits in an HBitmap. >> + * @start and @count must be aligned to bitmap granularity. The only >> exception >> + * is resetting the tail of the bitmap: @count may be equal to @start + >> + * hb->orig_size, > > s/@start + hb->orig_size/hb->orig_size - @start/, I think. Ha, I wanted to say start + count equal to orig_size. Yours is OK too of course. > >> in this case @count may be not aligned. @start + @count > > +are > > With those fixed: > > Reviewed-by: Max Reitz Thanks! > >> + * allowed to be greater than hb->orig_size, but only if @start < >> hb->orig_size >> + * and @start + @count = ALIGN_UP(hb->orig_size, granularity). >>*/ >> void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count); >> >> diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c >> index 592d8219db..2be56d1597 100644 >> --- a/tests/test-hbitmap.c >> +++ b/tests/test-hbitmap.c >> @@ -423,7 +423,7 @@ static void test_hbitmap_granularity(TestHBitmapData >> *data, >> hbitmap_test_check(data, 0); >> hbitmap_test_set(data, 0, 3); >> g_assert_cmpint(hbitmap_count(data->hb), ==, 4); >> -hbitmap_test_reset(data, 0, 1); >> +hbitmap_test_reset(data, 0, 2); >> g_assert_cmpint(hbitmap_count(data->hb), ==, 2); >> } >> >> diff --git a/util/hbitmap.c b/util/hbitmap.c >> index bcc0acdc6a..586920cb52 100644 >> --- a/util/hbitmap.c >> +++ b/util/hbitmap.c >> @@ -476,6 +476,10 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, >> uint64_t count) >> /* Compute range in the last layer. */ >> uint64_t first; >> uint64_t last = start + count - 1; >> +uint64_t gran = 1ULL << hb->granularity; >> + >> +assert(!(start & (gran - 1))); >> +assert(!(count & (gran - 1)) || (start + count == hb->orig_size)); >> >> trace_hbitmap_reset(hb, start, count, >> start >> hb->granularity, last >> hb->granularity); >> > > -- Best regards, Vladimir
Re: [Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
On 06.08.19 17:26, Vladimir Sementsov-Ogievskiy wrote: > hbitmap_reset has an unobvious property: it rounds requested region up. > It may provoke bugs, like in recently fixed write-blocking mode of > mirror: user calls reset on unaligned region, not keeping in mind that > there are possible unrelated dirty bytes, covered by rounded-up region > and information of this unrelated "dirtiness" will be lost. > > Make hbitmap_reset strict: assert that arguments are aligned, allowing > only one exception when @start + @count == hb->orig_size. It's needed > to comfort users of hbitmap_next_dirty_area, which cares about > hb->orig_size. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > > v2 based on Max's https://github.com/XanClic/qemu.git block > which will be merged soon to 4.1, and this patch goes to 4.2 > Based-on: https://github.com/XanClic/qemu.git block > > v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand > we all agreed to just assert alignment instead of aligning down > automatically. > > include/qemu/hbitmap.h | 5 + > tests/test-hbitmap.c | 2 +- > util/hbitmap.c | 4 > 3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h > index 4afbe6292e..7865e819ca 100644 > --- a/include/qemu/hbitmap.h > +++ b/include/qemu/hbitmap.h > @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t > count); > * @count: Number of bits to reset. > * > * Reset a consecutive range of bits in an HBitmap. > + * @start and @count must be aligned to bitmap granularity. The only > exception > + * is resetting the tail of the bitmap: @count may be equal to @start + > + * hb->orig_size, s/@start + hb->orig_size/hb->orig_size - @start/, I think. > in this case @count may be not aligned. @start + @count +are With those fixed: Reviewed-by: Max Reitz > + * allowed to be greater than hb->orig_size, but only if @start < > hb->orig_size > + * and @start + @count = ALIGN_UP(hb->orig_size, granularity). > */ > void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count); > > diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c > index 592d8219db..2be56d1597 100644 > --- a/tests/test-hbitmap.c > +++ b/tests/test-hbitmap.c > @@ -423,7 +423,7 @@ static void test_hbitmap_granularity(TestHBitmapData > *data, > hbitmap_test_check(data, 0); > hbitmap_test_set(data, 0, 3); > g_assert_cmpint(hbitmap_count(data->hb), ==, 4); > -hbitmap_test_reset(data, 0, 1); > +hbitmap_test_reset(data, 0, 2); > g_assert_cmpint(hbitmap_count(data->hb), ==, 2); > } > > diff --git a/util/hbitmap.c b/util/hbitmap.c > index bcc0acdc6a..586920cb52 100644 > --- a/util/hbitmap.c > +++ b/util/hbitmap.c > @@ -476,6 +476,10 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t > count) > /* Compute range in the last layer. */ > uint64_t first; > uint64_t last = start + count - 1; > +uint64_t gran = 1ULL << hb->granularity; > + > +assert(!(start & (gran - 1))); > +assert(!(count & (gran - 1)) || (start + count == hb->orig_size)); > > trace_hbitmap_reset(hb, start, count, > start >> hb->granularity, last >> hb->granularity); > signature.asc Description: OpenPGP digital signature
[Qemu-devel] [PATCH v2] util/hbitmap: strict hbitmap_reset
hbitmap_reset has an unobvious property: it rounds requested region up. It may provoke bugs, like in recently fixed write-blocking mode of mirror: user calls reset on unaligned region, not keeping in mind that there are possible unrelated dirty bytes, covered by rounded-up region and information of this unrelated "dirtiness" will be lost. Make hbitmap_reset strict: assert that arguments are aligned, allowing only one exception when @start + @count == hb->orig_size. It's needed to comfort users of hbitmap_next_dirty_area, which cares about hb->orig_size. Signed-off-by: Vladimir Sementsov-Ogievskiy --- v2 based on Max's https://github.com/XanClic/qemu.git block which will be merged soon to 4.1, and this patch goes to 4.2 Based-on: https://github.com/XanClic/qemu.git block v1 was "[PATCH] util/hbitmap: fix unaligned reset", and as I understand we all agreed to just assert alignment instead of aligning down automatically. include/qemu/hbitmap.h | 5 + tests/test-hbitmap.c | 2 +- util/hbitmap.c | 4 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h index 4afbe6292e..7865e819ca 100644 --- a/include/qemu/hbitmap.h +++ b/include/qemu/hbitmap.h @@ -132,6 +132,11 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count); * @count: Number of bits to reset. * * Reset a consecutive range of bits in an HBitmap. + * @start and @count must be aligned to bitmap granularity. The only exception + * is resetting the tail of the bitmap: @count may be equal to @start + + * hb->orig_size, in this case @count may be not aligned. @start + @count + * allowed to be greater than hb->orig_size, but only if @start < hb->orig_size + * and @start + @count = ALIGN_UP(hb->orig_size, granularity). */ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count); diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c index 592d8219db..2be56d1597 100644 --- a/tests/test-hbitmap.c +++ b/tests/test-hbitmap.c @@ -423,7 +423,7 @@ static void test_hbitmap_granularity(TestHBitmapData *data, hbitmap_test_check(data, 0); hbitmap_test_set(data, 0, 3); g_assert_cmpint(hbitmap_count(data->hb), ==, 4); -hbitmap_test_reset(data, 0, 1); +hbitmap_test_reset(data, 0, 2); g_assert_cmpint(hbitmap_count(data->hb), ==, 2); } diff --git a/util/hbitmap.c b/util/hbitmap.c index bcc0acdc6a..586920cb52 100644 --- a/util/hbitmap.c +++ b/util/hbitmap.c @@ -476,6 +476,10 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count) /* Compute range in the last layer. */ uint64_t first; uint64_t last = start + count - 1; +uint64_t gran = 1ULL << hb->granularity; + +assert(!(start & (gran - 1))); +assert(!(count & (gran - 1)) || (start + count == hb->orig_size)); trace_hbitmap_reset(hb, start, count, start >> hb->granularity, last >> hb->granularity); -- 2.18.0
