| Message ID | 20240605081605.18769-2-pstanner@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Make PCI's devres API more consistent | expand |
On Wed, Jun 05, 2024 at 10:15:52AM +0200, Philipp Stanner wrote: > Hello Bjorn, > > I tried to meet your requests from the last feedback round as much as > possible. Especially, I removed a lot of code, made almost all > interfaces private and cut the series into smaller chunks where > possible. > > Splitting it even smaller is unfortunately not possible because of the > Linux kernel build chain's rule on dead / unused code. > > See also the changelog below. > > Please tell me if that's enough to move forward here. > > Regards, > P. > > > Changes in v7: > - Split the entire series in smaller, more atomic chunks / patches > (Bjorn) > - Remove functions (such as pcim_iomap_region_range()) that do not yet > have a user (Bjorn) > - Don't export interfaces publicly anymore, except for > pcim_iomap_range(), needed by vboxvideo (Bjorn) > - Mention the actual (vboxvideo) bug in "PCI: Warn users..." commit > (Bjorn) > - Drop docstring warnings on PCI-internal functions (Bjorn) > - Rework docstring warnings > - Fix spelling in a few places. Rewrapp paragraphs (Bjorn) > > Changes in v6: > - Restructure the cleanup in pcim_iomap_regions_request_all() so that > it doesn't trigger a (false positive) test robot warning. No > behavior change intended. (Dan Carpenter) > > Changes in v5: > - Add Hans's Reviewed-by to vboxvideo patch (Hans de Goede) > - Remove stable-kernel from CC in vboxvideo patch (Hans de Goede) > > Changes in v4: > - Rebase against linux-next > > Changes in v3: > - Use the term "PCI devres API" at some forgotten places. > - Fix more grammar errors in patch #3. > - Remove the comment advising to call (the outdated) pcim_intx() in pci.c > - Rename __pcim_request_region_range() flags-field "exclusive" to > "req_flags", since this is what the int actually represents. > - Remove the call to pcim_region_request() from patch #10. (Hans) > > Changes in v2: > - Make commit head lines congruent with PCI's style (Bjorn) > - Add missing error checks for devm_add_action(). (Andy) > - Repair the "Returns: " marks for docu generation (Andy) > - Initialize the addr_devres struct with memset(). (Andy) > - Make pcim_intx() a PCI-internal function so that new drivers won't > be encouraged to use the outdated pci_intx() mechanism. > (Andy / Philipp) > - Fix grammar and spelling (Bjorn) > - Be more precise on why pcim_iomap_table() is problematic (Bjorn) > - Provide the actual structs' and functions' names in the commit > messages (Bjorn) > - Remove redundant variable initializers (Andy) > - Regroup PM bitfield members in struct pci_dev (Andy) > - Make pcim_intx() visible only for the PCI subsystem so that new > drivers won't use this outdated API (Andy, Myself) > - Add a NOTE to pcim_iomap() to warn about this function being the onee > xception that does just return NULL. > - Consistently use the term "PCI devres API"; also in Patch #10 (Bjorn) > > > ¡Hola! > > PCI's devres API suffers several weaknesses: > > 1. There are functions prefixed with pcim_. Those are always managed > counterparts to never-managed functions prefixed with pci_ – or so one > would like to think. There are some apparently unmanaged functions > (all region-request / release functions, and pci_intx()) which > suddenly become managed once the user has initialized the device with > pcim_enable_device() instead of pci_enable_device(). This "sometimes > yes, sometimes no" nature of those functions is confusing and > therefore bug-provoking. In fact, it has already caused a bug in DRM. > The last patch in this series fixes that bug. > 2. iomappings: Instead of giving each mapping its own callback, the > existing API uses a statically allocated struct tracking one mapping > per bar. This is not extensible. Especially, you can't create > _ranged_ managed mappings that way, which many drivers want. > 3. Managed request functions only exist as "plural versions" with a > bit-mask as a parameter. That's quite over-engineered considering > that each user only ever mapps one, maybe two bars. > > This series: > - add a set of new "singular" devres functions that use devres the way > its intended, with one callback per resource. > - deprecates the existing iomap-table mechanism. > - deprecates the hybrid nature of pci_ functions. > - preserves backwards compatibility so that drivers using the existing > API won't notice any changes. > - adds documentation, especially some warning users about the > complicated nature of PCI's devres. > > > Note that this series is based on my "unify pci_iounmap"-series from a > few weeks ago. [1] > > I tested this on a x86 VM with a simple pci test-device with two > regions. Operates and reserves resources as intended on my system. > Kasan and kmemleak didn't find any problems. > > I believe this series cleans the API up as much as possible without > having to port all existing drivers to the new API. Especially, I think > that this implementation is easy to extend if the need for new managed > functions arises :) > > Greetings, > P. > > Philipp Stanner (13): > PCI: Add and use devres helper for bit masks > PCI: Add devres helpers for iomap table > PCI: Reimplement plural devres functions > PCI: Deprecate two surplus devres functions > PCI: Make devres region requests consistent > PCI: Warn users about complicated devres nature Applied the above to pci/devres for v6.11 with minor comment and whitespace tweaks. Will watch for updates for the ones below to consolidate "enabled" and "enable_cnt". > PCI: Move dev-enabled status bit to struct pci_dev > PCI: Move pinned status bit to struct pci_dev > PCI: Give pcim_set_mwi() its own devres callback > PCI: Give pci(m)_intx its own devres callback > PCI: Remove legacy pcim_release() > PCI: Add pcim_iomap_range() > drm/vboxvideo: fix mapping leaks > > drivers/gpu/drm/vboxvideo/vbox_main.c | 20 +- > drivers/pci/devres.c | 897 +++++++++++++++++++++----- > drivers/pci/iomap.c | 16 + > drivers/pci/pci.c | 107 ++- > drivers/pci/pci.h | 23 +- > include/linux/pci.h | 6 +- > 6 files changed, 864 insertions(+), 205 deletions(-) > > -- > 2.45.0 >
Hello Bjorn, I tried to meet your requests from the last feedback round as much as possible. Especially, I removed a lot of code, made almost all interfaces private and cut the series into smaller chunks where possible. Splitting it even smaller is unfortunately not possible because of the Linux kernel build chain's rule on dead / unused code. See also the changelog below. Please tell me if that's enough to move forward here. Regards, P. Changes in v7: - Split the entire series in smaller, more atomic chunks / patches (Bjorn) - Remove functions (such as pcim_iomap_region_range()) that do not yet have a user (Bjorn) - Don't export interfaces publicly anymore, except for pcim_iomap_range(), needed by vboxvideo (Bjorn) - Mention the actual (vboxvideo) bug in "PCI: Warn users..." commit (Bjorn) - Drop docstring warnings on PCI-internal functions (Bjorn) - Rework docstring warnings - Fix spelling in a few places. Rewrapp paragraphs (Bjorn) Changes in v6: - Restructure the cleanup in pcim_iomap_regions_request_all() so that it doesn't trigger a (false positive) test robot warning. No behavior change intended. (Dan Carpenter) Changes in v5: - Add Hans's Reviewed-by to vboxvideo patch (Hans de Goede) - Remove stable-kernel from CC in vboxvideo patch (Hans de Goede) Changes in v4: - Rebase against linux-next Changes in v3: - Use the term "PCI devres API" at some forgotten places. - Fix more grammar errors in patch #3. - Remove the comment advising to call (the outdated) pcim_intx() in pci.c - Rename __pcim_request_region_range() flags-field "exclusive" to "req_flags", since this is what the int actually represents. - Remove the call to pcim_region_request() from patch #10. (Hans) Changes in v2: - Make commit head lines congruent with PCI's style (Bjorn) - Add missing error checks for devm_add_action(). (Andy) - Repair the "Returns: " marks for docu generation (Andy) - Initialize the addr_devres struct with memset(). (Andy) - Make pcim_intx() a PCI-internal function so that new drivers won't be encouraged to use the outdated pci_intx() mechanism. (Andy / Philipp) - Fix grammar and spelling (Bjorn) - Be more precise on why pcim_iomap_table() is problematic (Bjorn) - Provide the actual structs' and functions' names in the commit messages (Bjorn) - Remove redundant variable initializers (Andy) - Regroup PM bitfield members in struct pci_dev (Andy) - Make pcim_intx() visible only for the PCI subsystem so that new drivers won't use this outdated API (Andy, Myself) - Add a NOTE to pcim_iomap() to warn about this function being the onee xception that does just return NULL. - Consistently use the term "PCI devres API"; also in Patch #10 (Bjorn) ¡Hola! PCI's devres API suffers several weaknesses: 1. There are functions prefixed with pcim_. Those are always managed counterparts to never-managed functions prefixed with pci_ – or so one would like to think. There are some apparently unmanaged functions (all region-request / release functions, and pci_intx()) which suddenly become managed once the user has initialized the device with pcim_enable_device() instead of pci_enable_device(). This "sometimes yes, sometimes no" nature of those functions is confusing and therefore bug-provoking. In fact, it has already caused a bug in DRM. The last patch in this series fixes that bug. 2. iomappings: Instead of giving each mapping its own callback, the existing API uses a statically allocated struct tracking one mapping per bar. This is not extensible. Especially, you can't create _ranged_ managed mappings that way, which many drivers want. 3. Managed request functions only exist as "plural versions" with a bit-mask as a parameter. That's quite over-engineered considering that each user only ever mapps one, maybe two bars. This series: - add a set of new "singular" devres functions that use devres the way its intended, with one callback per resource. - deprecates the existing iomap-table mechanism. - deprecates the hybrid nature of pci_ functions. - preserves backwards compatibility so that drivers using the existing API won't notice any changes. - adds documentation, especially some warning users about the complicated nature of PCI's devres. Note that this series is based on my "unify pci_iounmap"-series from a few weeks ago. [1] I tested this on a x86 VM with a simple pci test-device with two regions. Operates and reserves resources as intended on my system. Kasan and kmemleak didn't find any problems. I believe this series cleans the API up as much as possible without having to port all existing drivers to the new API. Especially, I think that this implementation is easy to extend if the need for new managed functions arises :) Greetings, P. Philipp Stanner (13): PCI: Add and use devres helper for bit masks PCI: Add devres helpers for iomap table PCI: Reimplement plural devres functions PCI: Deprecate two surplus devres functions PCI: Make devres region requests consistent PCI: Warn users about complicated devres nature PCI: Move dev-enabled status bit to struct pci_dev PCI: Move pinned status bit to struct pci_dev PCI: Give pcim_set_mwi() its own devres callback PCI: Give pci(m)_intx its own devres callback PCI: Remove legacy pcim_release() PCI: Add pcim_iomap_range() drm/vboxvideo: fix mapping leaks drivers/gpu/drm/vboxvideo/vbox_main.c | 20 +- drivers/pci/devres.c | 897 +++++++++++++++++++++----- drivers/pci/iomap.c | 16 + drivers/pci/pci.c | 107 ++- drivers/pci/pci.h | 23 +- include/linux/pci.h | 6 +- 6 files changed, 864 insertions(+), 205 deletions(-)