| Message ID | 20210117160754.4086411-1-f4bug@amsat.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | softmmu/physmem: Hint notifier is not NULL in as_translate_for_iotlb() | expand |
On Sun, 17 Jan 2021 at 16:07, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: > > When using GCC 10.2 configured with --extra-cflags=-Os, we get: > > softmmu/physmem.c: In function ‘address_space_translate_for_iotlb’: > softmmu/physmem.c:643:26: error: ‘notifier’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > 643 | notifier->active = true; > | ^ > softmmu/physmem.c:608:23: note: ‘notifier’ was declared here > 608 | TCGIOMMUNotifier *notifier; > | ^~~~~~~~ > > Insert assertions as hint to the compiler that 'notifier' can > not be NULL there. > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > Yet another hole in our CI. > --- > softmmu/physmem.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/softmmu/physmem.c b/softmmu/physmem.c > index 6301f4f0a5c..65602ed548e 100644 > --- a/softmmu/physmem.c > +++ b/softmmu/physmem.c > @@ -605,7 +605,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, > * when the IOMMU tells us the mappings we've cached have changed. > */ > MemoryRegion *mr = MEMORY_REGION(iommu_mr); > - TCGIOMMUNotifier *notifier; > + TCGIOMMUNotifier *notifier = NULL; > int i; > > for (i = 0; i < cpu->iommu_notifiers->len; i++) { > @@ -638,6 +638,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, > memory_region_register_iommu_notifier(notifier->mr, ¬ifier->n, > &error_fatal); > } > + assert(notifier != NULL); > > if (!notifier->active) { > notifier->active = true; Is the assert() necessary to prevent the compiler complaining? Usually we don't bother if it's about to be dereferenced anyway. thanks -- PMM
On 1/17/21 5:47 PM, Peter Maydell wrote: > On Sun, 17 Jan 2021 at 16:07, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: >> >> When using GCC 10.2 configured with --extra-cflags=-Os, we get: >> >> softmmu/physmem.c: In function ‘address_space_translate_for_iotlb’: >> softmmu/physmem.c:643:26: error: ‘notifier’ may be used uninitialized in this function [-Werror=maybe-uninitialized] >> 643 | notifier->active = true; >> | ^ >> softmmu/physmem.c:608:23: note: ‘notifier’ was declared here >> 608 | TCGIOMMUNotifier *notifier; >> | ^~~~~~~~ >> >> Insert assertions as hint to the compiler that 'notifier' can >> not be NULL there. >> >> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> >> --- >> Yet another hole in our CI. >> --- >> softmmu/physmem.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/softmmu/physmem.c b/softmmu/physmem.c >> index 6301f4f0a5c..65602ed548e 100644 >> --- a/softmmu/physmem.c >> +++ b/softmmu/physmem.c >> @@ -605,7 +605,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, >> * when the IOMMU tells us the mappings we've cached have changed. >> */ >> MemoryRegion *mr = MEMORY_REGION(iommu_mr); >> - TCGIOMMUNotifier *notifier; >> + TCGIOMMUNotifier *notifier = NULL; >> int i; >> >> for (i = 0; i < cpu->iommu_notifiers->len; i++) { >> @@ -638,6 +638,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, >> memory_region_register_iommu_notifier(notifier->mr, ¬ifier->n, >> &error_fatal); >> } >> + assert(notifier != NULL); >> >> if (!notifier->active) { >> notifier->active = true; > > Is the assert() necessary to prevent the compiler complaining? > Usually we don't bother if it's about to be dereferenced anyway. Yes you are right, the assert() is not necessary. Simply initializing the value silents the error. Regards, Phil.
diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 6301f4f0a5c..65602ed548e 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -605,7 +605,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, * when the IOMMU tells us the mappings we've cached have changed. */ MemoryRegion *mr = MEMORY_REGION(iommu_mr); - TCGIOMMUNotifier *notifier; + TCGIOMMUNotifier *notifier = NULL; int i; for (i = 0; i < cpu->iommu_notifiers->len; i++) { @@ -638,6 +638,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu, memory_region_register_iommu_notifier(notifier->mr, ¬ifier->n, &error_fatal); } + assert(notifier != NULL); if (!notifier->active) { notifier->active = true;
When using GCC 10.2 configured with --extra-cflags=-Os, we get: softmmu/physmem.c: In function ‘address_space_translate_for_iotlb’: softmmu/physmem.c:643:26: error: ‘notifier’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 643 | notifier->active = true; | ^ softmmu/physmem.c:608:23: note: ‘notifier’ was declared here 608 | TCGIOMMUNotifier *notifier; | ^~~~~~~~ Insert assertions as hint to the compiler that 'notifier' can not be NULL there. Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> --- Yet another hole in our CI. --- softmmu/physmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)