| Message ID | 20220425112751.25985-4-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fbdev: Decouple deferred I/O from struct page | expand |
Hi Thomas. On Mon, Apr 25, 2022 at 01:27:51PM +0200, Thomas Zimmermann wrote: > Refactor the page-write handler for deferred I/O. Drivers use the > function to let fbdev track written pages of mmap'ed framebuffer > memory. I like how the comments got a brush up and a little more info was added. But I do not see the point of the refactoring - the code is equally readable before and after - maybe even easier before (modulus the improved comments). But if you consider it better keep it. Again just my thoughts when reading the code. Sam > > v2: > * don't export the helper until we have an external caller > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> > --- > drivers/video/fbdev/core/fb_defio.c | 68 ++++++++++++++++++++--------- > 1 file changed, 48 insertions(+), 20 deletions(-) > > diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c > index a03b9c64fc61..214581ce5840 100644 > --- a/drivers/video/fbdev/core/fb_defio.c > +++ b/drivers/video/fbdev/core/fb_defio.c > @@ -143,29 +143,18 @@ int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasy > } > EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); > > -/* vm_ops->page_mkwrite handler */ > -static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) > +/* > + * Adds a page to the dirty list. Requires caller to hold > + * struct fb_deferred_io.lock. Call this from struct > + * vm_operations_struct.page_mkwrite. > + */ > +static vm_fault_t __fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, > + struct page *page) > { > - struct page *page = vmf->page; > - struct fb_info *info = vmf->vma->vm_private_data; > struct fb_deferred_io *fbdefio = info->fbdefio; > struct fb_deferred_io_pageref *pageref; > - unsigned long offset; > vm_fault_t ret; > > - offset = (vmf->address - vmf->vma->vm_start); > - > - /* this is a callback we get when userspace first tries to > - write to the page. we schedule a workqueue. that workqueue > - will eventually mkclean the touched pages and execute the > - deferred framebuffer IO. then if userspace touches a page > - again, we repeat the same scheme */ > - > - file_update_time(vmf->vma->vm_file); > - > - /* protect against the workqueue changing the page list */ > - mutex_lock(&fbdefio->lock); > - > /* first write in this cycle, notify the driver */ > if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) > fbdefio->first_io(info); > @@ -186,8 +175,6 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) > */ > lock_page(pageref->page); > > - mutex_unlock(&fbdefio->lock); > - > /* come back after delay to process the deferred IO */ > schedule_delayed_work(&info->deferred_work, fbdefio->delay); > return VM_FAULT_LOCKED; > @@ -197,6 +184,47 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) > return ret; > } > > +/* > + * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O > + * @fb_info: The fbdev info structure > + * @vmf: The VM fault > + * > + * This is a callback we get when userspace first tries to > + * write to the page. We schedule a workqueue. That workqueue > + * will eventually mkclean the touched pages and execute the > + * deferred framebuffer IO. Then if userspace touches a page > + * again, we repeat the same scheme. > + * > + * Returns: > + * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. > + */ > +static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) > +{ > + struct page *page = vmf->page; > + struct fb_deferred_io *fbdefio = info->fbdefio; > + unsigned long offset; > + vm_fault_t ret; > + > + offset = (vmf->address - vmf->vma->vm_start); > + > + file_update_time(vmf->vma->vm_file); > + > + /* protect against the workqueue changing the page list */ > + mutex_lock(&fbdefio->lock); > + ret = __fb_deferred_io_track_page(info, offset, page); > + mutex_unlock(&fbdefio->lock); > + > + return ret; > +} > + > +/* vm_ops->page_mkwrite handler */ > +static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) > +{ > + struct fb_info *info = vmf->vma->vm_private_data; > + > + return fb_deferred_io_page_mkwrite(info, vmf); > +} > + > static const struct vm_operations_struct fb_deferred_io_vm_ops = { > .fault = fb_deferred_io_fault, > .page_mkwrite = fb_deferred_io_mkwrite, > -- > 2.36.0
Hi Am 25.04.22 um 20:24 schrieb Sam Ravnborg: > Hi Thomas. > > On Mon, Apr 25, 2022 at 01:27:51PM +0200, Thomas Zimmermann wrote: >> Refactor the page-write handler for deferred I/O. Drivers use the >> function to let fbdev track written pages of mmap'ed framebuffer >> memory. > > I like how the comments got a brush up and a little more info was added. > But I do not see the point of the refactoring - the code is equally > readable before and after - maybe even easier before (modulus the > improved comments). > > But if you consider it better keep it. Again just my thoughts when > reading the code. The comes from patch of the larger GEM refactoring patches. [1] fb_deferred_io_page_mkwrite() is later supposed to be exported for use with DRM. The patch isn't strictly necessary, but it doesn't do any harm either. I added it to the patchset, so that I don't have to deal with potential bit rot later on. Best regards Thomas [1] https://lore.kernel.org/dri-devel/20220303205839.28484-5-tzimmermann@suse.de/ > > Sam > >> >> v2: >> * don't export the helper until we have an external caller >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> >> --- >> drivers/video/fbdev/core/fb_defio.c | 68 ++++++++++++++++++++--------- >> 1 file changed, 48 insertions(+), 20 deletions(-) >> >> diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c >> index a03b9c64fc61..214581ce5840 100644 >> --- a/drivers/video/fbdev/core/fb_defio.c >> +++ b/drivers/video/fbdev/core/fb_defio.c >> @@ -143,29 +143,18 @@ int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasy >> } >> EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); >> >> -/* vm_ops->page_mkwrite handler */ >> -static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> +/* >> + * Adds a page to the dirty list. Requires caller to hold >> + * struct fb_deferred_io.lock. Call this from struct >> + * vm_operations_struct.page_mkwrite. >> + */ >> +static vm_fault_t __fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, >> + struct page *page) >> { >> - struct page *page = vmf->page; >> - struct fb_info *info = vmf->vma->vm_private_data; >> struct fb_deferred_io *fbdefio = info->fbdefio; >> struct fb_deferred_io_pageref *pageref; >> - unsigned long offset; >> vm_fault_t ret; >> >> - offset = (vmf->address - vmf->vma->vm_start); >> - >> - /* this is a callback we get when userspace first tries to >> - write to the page. we schedule a workqueue. that workqueue >> - will eventually mkclean the touched pages and execute the >> - deferred framebuffer IO. then if userspace touches a page >> - again, we repeat the same scheme */ >> - >> - file_update_time(vmf->vma->vm_file); >> - >> - /* protect against the workqueue changing the page list */ >> - mutex_lock(&fbdefio->lock); >> - >> /* first write in this cycle, notify the driver */ >> if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) >> fbdefio->first_io(info); >> @@ -186,8 +175,6 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> */ >> lock_page(pageref->page); >> >> - mutex_unlock(&fbdefio->lock); >> - >> /* come back after delay to process the deferred IO */ >> schedule_delayed_work(&info->deferred_work, fbdefio->delay); >> return VM_FAULT_LOCKED; >> @@ -197,6 +184,47 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> return ret; >> } >> >> +/* >> + * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O >> + * @fb_info: The fbdev info structure >> + * @vmf: The VM fault >> + * >> + * This is a callback we get when userspace first tries to >> + * write to the page. We schedule a workqueue. That workqueue >> + * will eventually mkclean the touched pages and execute the >> + * deferred framebuffer IO. Then if userspace touches a page >> + * again, we repeat the same scheme. >> + * >> + * Returns: >> + * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. >> + */ >> +static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) >> +{ >> + struct page *page = vmf->page; >> + struct fb_deferred_io *fbdefio = info->fbdefio; >> + unsigned long offset; >> + vm_fault_t ret; >> + >> + offset = (vmf->address - vmf->vma->vm_start); >> + >> + file_update_time(vmf->vma->vm_file); >> + >> + /* protect against the workqueue changing the page list */ >> + mutex_lock(&fbdefio->lock); >> + ret = __fb_deferred_io_track_page(info, offset, page); >> + mutex_unlock(&fbdefio->lock); >> + >> + return ret; >> +} >> + >> +/* vm_ops->page_mkwrite handler */ >> +static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> +{ >> + struct fb_info *info = vmf->vma->vm_private_data; >> + >> + return fb_deferred_io_page_mkwrite(info, vmf); >> +} >> + >> static const struct vm_operations_struct fb_deferred_io_vm_ops = { >> .fault = fb_deferred_io_fault, >> .page_mkwrite = fb_deferred_io_mkwrite, >> -- >> 2.36.0
Hi Am 25.04.22 um 20:24 schrieb Sam Ravnborg: > Hi Thomas. > > On Mon, Apr 25, 2022 at 01:27:51PM +0200, Thomas Zimmermann wrote: >> Refactor the page-write handler for deferred I/O. Drivers use the >> function to let fbdev track written pages of mmap'ed framebuffer >> memory. > > I like how the comments got a brush up and a little more info was added. > But I do not see the point of the refactoring - the code is equally > readable before and after - maybe even easier before (modulus the > improved comments). FYI I'm going to move the locking into the track-page helper, which makes the code more readable. Best regards Thomas > > But if you consider it better keep it. Again just my thoughts when > reading the code. > > Sam > >> >> v2: >> * don't export the helper until we have an external caller >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> >> --- >> drivers/video/fbdev/core/fb_defio.c | 68 ++++++++++++++++++++--------- >> 1 file changed, 48 insertions(+), 20 deletions(-) >> >> diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c >> index a03b9c64fc61..214581ce5840 100644 >> --- a/drivers/video/fbdev/core/fb_defio.c >> +++ b/drivers/video/fbdev/core/fb_defio.c >> @@ -143,29 +143,18 @@ int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasy >> } >> EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); >> >> -/* vm_ops->page_mkwrite handler */ >> -static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> +/* >> + * Adds a page to the dirty list. Requires caller to hold >> + * struct fb_deferred_io.lock. Call this from struct >> + * vm_operations_struct.page_mkwrite. >> + */ >> +static vm_fault_t __fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, >> + struct page *page) >> { >> - struct page *page = vmf->page; >> - struct fb_info *info = vmf->vma->vm_private_data; >> struct fb_deferred_io *fbdefio = info->fbdefio; >> struct fb_deferred_io_pageref *pageref; >> - unsigned long offset; >> vm_fault_t ret; >> >> - offset = (vmf->address - vmf->vma->vm_start); >> - >> - /* this is a callback we get when userspace first tries to >> - write to the page. we schedule a workqueue. that workqueue >> - will eventually mkclean the touched pages and execute the >> - deferred framebuffer IO. then if userspace touches a page >> - again, we repeat the same scheme */ >> - >> - file_update_time(vmf->vma->vm_file); >> - >> - /* protect against the workqueue changing the page list */ >> - mutex_lock(&fbdefio->lock); >> - >> /* first write in this cycle, notify the driver */ >> if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) >> fbdefio->first_io(info); >> @@ -186,8 +175,6 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> */ >> lock_page(pageref->page); >> >> - mutex_unlock(&fbdefio->lock); >> - >> /* come back after delay to process the deferred IO */ >> schedule_delayed_work(&info->deferred_work, fbdefio->delay); >> return VM_FAULT_LOCKED; >> @@ -197,6 +184,47 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> return ret; >> } >> >> +/* >> + * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O >> + * @fb_info: The fbdev info structure >> + * @vmf: The VM fault >> + * >> + * This is a callback we get when userspace first tries to >> + * write to the page. We schedule a workqueue. That workqueue >> + * will eventually mkclean the touched pages and execute the >> + * deferred framebuffer IO. Then if userspace touches a page >> + * again, we repeat the same scheme. >> + * >> + * Returns: >> + * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. >> + */ >> +static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) >> +{ >> + struct page *page = vmf->page; >> + struct fb_deferred_io *fbdefio = info->fbdefio; >> + unsigned long offset; >> + vm_fault_t ret; >> + >> + offset = (vmf->address - vmf->vma->vm_start); >> + >> + file_update_time(vmf->vma->vm_file); >> + >> + /* protect against the workqueue changing the page list */ >> + mutex_lock(&fbdefio->lock); >> + ret = __fb_deferred_io_track_page(info, offset, page); >> + mutex_unlock(&fbdefio->lock); >> + >> + return ret; >> +} >> + >> +/* vm_ops->page_mkwrite handler */ >> +static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) >> +{ >> + struct fb_info *info = vmf->vma->vm_private_data; >> + >> + return fb_deferred_io_page_mkwrite(info, vmf); >> +} >> + >> static const struct vm_operations_struct fb_deferred_io_vm_ops = { >> .fault = fb_deferred_io_fault, >> .page_mkwrite = fb_deferred_io_mkwrite, >> -- >> 2.36.0
diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index a03b9c64fc61..214581ce5840 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -143,29 +143,18 @@ int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasy } EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); -/* vm_ops->page_mkwrite handler */ -static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) +/* + * Adds a page to the dirty list. Requires caller to hold + * struct fb_deferred_io.lock. Call this from struct + * vm_operations_struct.page_mkwrite. + */ +static vm_fault_t __fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, + struct page *page) { - struct page *page = vmf->page; - struct fb_info *info = vmf->vma->vm_private_data; struct fb_deferred_io *fbdefio = info->fbdefio; struct fb_deferred_io_pageref *pageref; - unsigned long offset; vm_fault_t ret; - offset = (vmf->address - vmf->vma->vm_start); - - /* this is a callback we get when userspace first tries to - write to the page. we schedule a workqueue. that workqueue - will eventually mkclean the touched pages and execute the - deferred framebuffer IO. then if userspace touches a page - again, we repeat the same scheme */ - - file_update_time(vmf->vma->vm_file); - - /* protect against the workqueue changing the page list */ - mutex_lock(&fbdefio->lock); - /* first write in this cycle, notify the driver */ if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) fbdefio->first_io(info); @@ -186,8 +175,6 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) */ lock_page(pageref->page); - mutex_unlock(&fbdefio->lock); - /* come back after delay to process the deferred IO */ schedule_delayed_work(&info->deferred_work, fbdefio->delay); return VM_FAULT_LOCKED; @@ -197,6 +184,47 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) return ret; } +/* + * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O + * @fb_info: The fbdev info structure + * @vmf: The VM fault + * + * This is a callback we get when userspace first tries to + * write to the page. We schedule a workqueue. That workqueue + * will eventually mkclean the touched pages and execute the + * deferred framebuffer IO. Then if userspace touches a page + * again, we repeat the same scheme. + * + * Returns: + * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. + */ +static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) +{ + struct page *page = vmf->page; + struct fb_deferred_io *fbdefio = info->fbdefio; + unsigned long offset; + vm_fault_t ret; + + offset = (vmf->address - vmf->vma->vm_start); + + file_update_time(vmf->vma->vm_file); + + /* protect against the workqueue changing the page list */ + mutex_lock(&fbdefio->lock); + ret = __fb_deferred_io_track_page(info, offset, page); + mutex_unlock(&fbdefio->lock); + + return ret; +} + +/* vm_ops->page_mkwrite handler */ +static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) +{ + struct fb_info *info = vmf->vma->vm_private_data; + + return fb_deferred_io_page_mkwrite(info, vmf); +} + static const struct vm_operations_struct fb_deferred_io_vm_ops = { .fault = fb_deferred_io_fault, .page_mkwrite = fb_deferred_io_mkwrite,