* Re: [RFC PATCH] vfio: type1: fix kthread use case [not found] <20200706104915.11460-1-hdanton@sina.com> @ 2020-07-06 11:32 ` Markus Elfring [not found] ` <20200706124241.4392-1-hdanton@sina.com> 1 sibling, 0 replies; 4+ messages in thread From: Markus Elfring @ 2020-07-06 11:32 UTC (permalink / raw) To: Hillf Danton, Alex Williamson, iommu Cc: Kevin Tian, Yan Zhao, kernel-janitors, linux-kernel, Christoph Hellwig … > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -2798,7 +2798,8 @@ static int vfio_iommu_type1_dma_rw_chunk … > - bool kthread = current->mm == NULL; > + bool kthread = current->flags & PF_KTHREAD; > + bool use_mm = current->mm == NULL; … Can it be helpful to convert initialisations for these variables into later assignments? Regards, Markus ^ permalink raw reply [flat|nested] 4+ messages in thread
[parent not found: <20200706124241.4392-1-hdanton@sina.com>]
* Re: [RFC PATCH] vfio: type1: fix kthread use case [not found] ` <20200706124241.4392-1-hdanton@sina.com> @ 2020-07-06 13:33 ` Markus Elfring 2020-07-06 14:04 ` Markus Elfring [not found] ` <20200707011420.1416-1-hdanton@sina.com> 2 siblings, 0 replies; 4+ messages in thread From: Markus Elfring @ 2020-07-06 13:33 UTC (permalink / raw) To: Hillf Danton, Alex Williamson, iommu Cc: Kevin Tian, Yan Zhao, kernel-janitors, linux-kernel, Christoph Hellwig >> Can it be helpful to convert initialisations for these variables >> into later assignments? > > Perhaps. Then it looks like the below. … > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -2798,9 +2798,12 @@ static int vfio_iommu_type1_dma_rw_chunk … > - bool kthread = current->mm == NULL; > + bool kthread; > + bool use_mm; I would prefer the following variable declarations then. + bool kthread, use_mm; > size_t offset; > > + kthread = current->flags & PF_KTHREAD; > + use_mm = current->mm == NULL; I propose to move such assignments directly before the corresponding check. … > if (!mm) > return -EPERM; + kthread = current->flags & PF_KTHREAD; + use_mm = !current->mm; > - if (kthread) > + if (kthread && use_mm) > kthread_use_mm(mm); … Regards, Markus ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [RFC PATCH] vfio: type1: fix kthread use case [not found] ` <20200706124241.4392-1-hdanton@sina.com> 2020-07-06 13:33 ` Markus Elfring @ 2020-07-06 14:04 ` Markus Elfring [not found] ` <20200707011420.1416-1-hdanton@sina.com> 2 siblings, 0 replies; 4+ messages in thread From: Markus Elfring @ 2020-07-06 14:04 UTC (permalink / raw) To: Hillf Danton, Alex Williamson, iommu Cc: Kevin Tian, Yan Zhao, kernel-janitors, linux-kernel, Christoph Hellwig … > +++ b/drivers/vfio/vfio_iommu_type1.c … > @@ -2812,11 +2815,10 @@ static int vfio_iommu_type1_dma_rw_chunk … > if (!mm) > return -EPERM; > > - if (kthread) > + if (kthread && use_mm) Can another design approach make sense here? + bool thread_use_mm = ((current->flags & PF_KTHREAD) && !current->mm); + if (thread_use_mm) > kthread_use_mm(mm); … Regards, Markus ^ permalink raw reply [flat|nested] 4+ messages in thread
[parent not found: <20200707011420.1416-1-hdanton@sina.com>]
* Re: [RFC PATCH] vfio: type1: fix kthread use case [not found] ` <20200707011420.1416-1-hdanton@sina.com> @ 2020-07-07 6:04 ` Markus Elfring 0 siblings, 0 replies; 4+ messages in thread From: Markus Elfring @ 2020-07-07 6:04 UTC (permalink / raw) To: Hillf Danton, iommu Cc: Kevin Tian, Yan Zhao, kernel-janitors, linux-kernel, Alex Williamson, Christoph Hellwig … > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -2798,7 +2798,7 @@ static int vfio_iommu_type1_dma_rw_chunk … > - bool kthread = current->mm == NULL; > + bool kthread_load_mm; > size_t offset; How do you think about to reduce the scope for such variables? https://refactoring.com/catalog/reduceScopeOfVariable.html … > @@ -2812,11 +2812,12 @@ static int vfio_iommu_type1_dma_rw_chunk … > if (!mm) > return -EPERM; … > + kthread_load_mm = current->flags & PF_KTHREAD && > + current->mm == NULL; … Would you like to apply a more succinct code variant? + kthread_load_mm = current->flags & PF_KTHREAD && !current->mm; Regards, Markus ^ permalink raw reply [flat|nested] 4+ messages in thread
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