Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On 21/07/2014 17:16, Bjorn Helgaas wrote: [+cc Jingoo] On Fri, Jul 18, 2014 at 12:50 PM, James Bottomley Anyway, it's PCI code ... let the PCI maintainer decide. However, if he does want this do it as one big bang patch via either the PCI or Trivial tree (latter because Jiří has experience doing this, but the former might be useful so the decider feels the pain ...) I don't feel strongly either way, so I guess I'm OK with this, and in the spirit of feeling the pain, I'm willing to handle it. Jingoo proposed similar patches, so it might be nice to give him some credit. Benoit, how about if you wait until about half-way through the merge window after v3.16 releases, generate an up-to-date single patch, and post that? Then we can try to get it in before v3.17-rc1 to minimize merge hassles. Sure, I will do this. -- Benoît Taine Master cycle intern Regal Team. LIP6 ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
[+cc Jingoo] On Fri, Jul 18, 2014 at 12:50 PM, James Bottomley james.bottom...@hansenpartnership.com wrote: On Fri, 2014-07-18 at 11:17 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 09:54:32AM -0700, James Bottomley wrote: On Fri, 2014-07-18 at 09:43 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing OK, so this is the macro: #define DEFINE_PCI_DEVICE_TABLE(_table) \ const struct pci_device_id _table[] Could you explain what's so horrible? The reason it's useful today is that people forget the const (and sometimes the [] making it a true table instead of a pointer). If you use the DEFINE_PCI_DEVICE_TABLE macro, the compile breaks if you use it wrongly (good) and you automatically get the correct annotations. We have almost 1000 more uses of the non-macro version than the macro version in the kernel today: $ git grep -w DEFINE_PCI_DEVICE_TABLE | wc -l 262 $ git grep const struct pci_device_id | wc -l 1254 My big complaint is that we need to be consistant, either pick one or the other and stick to it. As the macro is the least used, it's easiest to fix up, and it also is more consistant with all other kernel subsystems which do not have such a macro. I've a weak preference for consistency, but not at the expense of hundreds of patches churning the kernel to remove an innocuous macro. Churn costs time and effort. As there is no need for the __init macro mess anymore, there's no real need for the DEFINE_PCI_DEVICE_TABLE macro either. I think checkpatch will catch the use of non-const users for the id table already today, it catches lots of other uses like this already. , so why should PCI be special in this regard anymore? I think the PCI usage dwarfs most other bus types now, so you could turn the question around. However, I don't think majority voting is a good guide to best practise; lets debate the merits for their own sake. Not really dwarf, USB is close with over 700 such structures: $ git grep const struct usb_device_id | wc -l 725 And i2c is almost just as big as PCI: $ git grep const struct i2c_device_id | wc -l 1223 So again, this macro is not consistent with the majority of PCI drivers, nor with any other type of device id declaration in the kernel, which is why I feel it should be removed. And finally, the PCI documentation itself says to not use this macro, so this isn't a new thing. From Documentation/PCI/pci.txt: The ID table is an array of struct pci_device_id entries ending with an all-zero entry. Definitions with static const are generally preferred. Use of the deprecated macro DEFINE_PCI_DEVICE_TABLE should be avoided. That wording went into the file last December, when we last talked about this and everyone in that discussion agreed to remove the macro for the above reasons. Consistency matters. In this case, I don't think it does that much ... a cut and paste either way (from a macro or non-macro based driver) yields correct code. Since there's no bug here and no apparent way to misuse the macro, why bother? Anyway, it's PCI code ... let the PCI maintainer decide. However, if he does want this do it as one big bang patch via either the PCI or Trivial tree (latter because Jiří has experience doing this, but the former might be useful so the decider feels the pain ...) I don't feel strongly either way, so I guess I'm OK with this, and in the spirit of feeling the pain, I'm willing to handle it. Jingoo proposed similar patches, so it might be nice to give him some credit. Benoit, how about if you wait until about half-way through the merge window after v3.16 releases, generate an up-to-date single patch, and post that? Then we can try to get it in before v3.17-rc1 to minimize merge hassles. Bjorn ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
[PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. A simplified version of the semantic patch that makes this change is as follows (http://coccinelle.lip6.fr/): // smpl @@ identifier i; declarer name DEFINE_PCI_DEVICE_TABLE; initializer z; @@ - DEFINE_PCI_DEVICE_TABLE(i) + const struct pci_device_id i[] = z; // /smpl I have 103 patches ready, and will only send a few for you to judge if it is useful enough, and to prevent from spamming too much. Thanks. ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, 2014-07-18 at 17:26 +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. What kernel coding style? checkpatch isn't the arbiter of style, if that's the only problem. The DEFINE_PCI macro was a well reasoned addition when it was added in 2008. The problem was most people were getting the definition wrong. When we converted away from CONFIG_HOTPLUG, having this DEFINE_ meant that only one place needed changing instead of hundreds for PCI tables. The reason people were getting the PCI table wrong was mostly the init section specifiers which are now gone, but it has enough underlying utility (mostly constification) that I don't think we'd want to churn the kernel hugely to make a change to struct pci_table and then have to start detecting and fixing misuses. James ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? John -- John W. LinvilleSomeday the world will need a hero, and you linvi...@tuxdriver.com might be all we have. Be ready. ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, 2014-07-18 at 09:28 -0700, James Bottomley wrote: On Fri, 2014-07-18 at 17:26 +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. What kernel coding style? checkpatch isn't the arbiter of style, if that's the only problem. The DEFINE_PCI macro was a well reasoned addition when it was added in 2008. The problem was most people were getting the definition wrong. When we converted away from CONFIG_HOTPLUG, having this DEFINE_ meant that only one place needed changing instead of hundreds for PCI tables. The reason people were getting the PCI table wrong was mostly the init section specifiers which are now gone, but it has enough underlying utility (mostly constification) that I don't think we'd want to churn the kernel hugely to make a change to struct pci_table and then have to start detecting and fixing misuses. James -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html I would rather fix the misuses of the macro, than remove it. Could we possibly make checkpatch smart enough to tell when the macro is misused? Thanks, Jake ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing, so why should PCI be special in this regard anymore? thanks, greg k-h ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, 2014-07-18 at 09:43 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing OK, so this is the macro: #define DEFINE_PCI_DEVICE_TABLE(_table) \ const struct pci_device_id _table[] Could you explain what's so horrible? The reason it's useful today is that people forget the const (and sometimes the [] making it a true table instead of a pointer). If you use the DEFINE_PCI_DEVICE_TABLE macro, the compile breaks if you use it wrongly (good) and you automatically get the correct annotations. , so why should PCI be special in this regard anymore? I think the PCI usage dwarfs most other bus types now, so you could turn the question around. However, I don't think majority voting is a good guide to best practise; lets debate the merits for their own sake. James ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, 2014-07-18 at 09:43 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. scripts/checkpatch.pl | 4 ++-- Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing, so why should PCI be special in this regard anymore? I think it doesn't matter much. The PCI_DEVICE and PCI_VDEVICE macro uses are somewhat similar and are frequently used with PCI_DEVICE_TABLE, so there's some commonality there. The checkpatch message could be made --strict/CHK instead of WARN so most people would never see it. Of course it could be removed altogether too. I don't care. --- (suggested patch is for -next) 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index dc72a9b..754fbf2 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -3018,8 +3018,8 @@ sub process { # check for uses of DEFINE_PCI_DEVICE_TABLE if ($line =~ /\bDEFINE_PCI_DEVICE_TABLE\s*\(\s*(\w+)\s*\)\s*=/) { - if (WARN(DEFINE_PCI_DEVICE_TABLE, -Prefer struct pci_device_id over deprecated DEFINE_PCI_DEVICE_TABLE\n . $herecurr) + if (CHK(DEFINE_PCI_DEVICE_TABLE, + Prefer struct pci_device_id over deprecated DEFINE_PCI_DEVICE_TABLE\n . $herecurr) $fix) { $fixed[$fixlinenr] =~ s/\b(?:static\s+|)DEFINE_PCI_DEVICE_TABLE\s*\(\s*(\w+)\s*\)\s*=\s*/static const struct pci_device_id $1\[\] = /; } ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, Jul 18, 2014 at 09:54:32AM -0700, James Bottomley wrote: On Fri, 2014-07-18 at 09:43 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing OK, so this is the macro: #define DEFINE_PCI_DEVICE_TABLE(_table) \ const struct pci_device_id _table[] Could you explain what's so horrible? The reason it's useful today is that people forget the const (and sometimes the [] making it a true table instead of a pointer). If you use the DEFINE_PCI_DEVICE_TABLE macro, the compile breaks if you use it wrongly (good) and you automatically get the correct annotations. We have almost 1000 more uses of the non-macro version than the macro version in the kernel today: $ git grep -w DEFINE_PCI_DEVICE_TABLE | wc -l 262 $ git grep const struct pci_device_id | wc -l 1254 My big complaint is that we need to be consistant, either pick one or the other and stick to it. As the macro is the least used, it's easiest to fix up, and it also is more consistant with all other kernel subsystems which do not have such a macro. As there is no need for the __init macro mess anymore, there's no real need for the DEFINE_PCI_DEVICE_TABLE macro either. I think checkpatch will catch the use of non-const users for the id table already today, it catches lots of other uses like this already. , so why should PCI be special in this regard anymore? I think the PCI usage dwarfs most other bus types now, so you could turn the question around. However, I don't think majority voting is a good guide to best practise; lets debate the merits for their own sake. Not really dwarf, USB is close with over 700 such structures: $ git grep const struct usb_device_id | wc -l 725 And i2c is almost just as big as PCI: $ git grep const struct i2c_device_id | wc -l 1223 So again, this macro is not consistent with the majority of PCI drivers, nor with any other type of device id declaration in the kernel, which is why I feel it should be removed. And finally, the PCI documentation itself says to not use this macro, so this isn't a new thing. From Documentation/PCI/pci.txt: The ID table is an array of struct pci_device_id entries ending with an all-zero entry. Definitions with static const are generally preferred. Use of the deprecated macro DEFINE_PCI_DEVICE_TABLE should be avoided. That wording went into the file last December, when we last talked about this and everyone in that discussion agreed to remove the macro for the above reasons. Consistency matters. thanks, greg k-h ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Fri, 2014-07-18 at 11:17 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 09:54:32AM -0700, James Bottomley wrote: On Fri, 2014-07-18 at 09:43 -0700, Greg KH wrote: On Fri, Jul 18, 2014 at 12:22:13PM -0400, John W. Linville wrote: On Fri, Jul 18, 2014 at 05:26:47PM +0200, Benoit Taine wrote: We should prefer `const struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet kernel coding style guidelines. This issue was reported by checkpatch. Honestly, I prefer the macro -- it stands-out more. Maybe the style guidelines and/or checkpatch should change instead? The macro is horrid, no other bus has this type of thing just to save a few characters in typing OK, so this is the macro: #define DEFINE_PCI_DEVICE_TABLE(_table) \ const struct pci_device_id _table[] Could you explain what's so horrible? The reason it's useful today is that people forget the const (and sometimes the [] making it a true table instead of a pointer). If you use the DEFINE_PCI_DEVICE_TABLE macro, the compile breaks if you use it wrongly (good) and you automatically get the correct annotations. We have almost 1000 more uses of the non-macro version than the macro version in the kernel today: $ git grep -w DEFINE_PCI_DEVICE_TABLE | wc -l 262 $ git grep const struct pci_device_id | wc -l 1254 My big complaint is that we need to be consistant, either pick one or the other and stick to it. As the macro is the least used, it's easiest to fix up, and it also is more consistant with all other kernel subsystems which do not have such a macro. I've a weak preference for consistency, but not at the expense of hundreds of patches churning the kernel to remove an innocuous macro. Churn costs time and effort. As there is no need for the __init macro mess anymore, there's no real need for the DEFINE_PCI_DEVICE_TABLE macro either. I think checkpatch will catch the use of non-const users for the id table already today, it catches lots of other uses like this already. , so why should PCI be special in this regard anymore? I think the PCI usage dwarfs most other bus types now, so you could turn the question around. However, I don't think majority voting is a good guide to best practise; lets debate the merits for their own sake. Not really dwarf, USB is close with over 700 such structures: $ git grep const struct usb_device_id | wc -l 725 And i2c is almost just as big as PCI: $ git grep const struct i2c_device_id | wc -l 1223 So again, this macro is not consistent with the majority of PCI drivers, nor with any other type of device id declaration in the kernel, which is why I feel it should be removed. And finally, the PCI documentation itself says to not use this macro, so this isn't a new thing. From Documentation/PCI/pci.txt: The ID table is an array of struct pci_device_id entries ending with an all-zero entry. Definitions with static const are generally preferred. Use of the deprecated macro DEFINE_PCI_DEVICE_TABLE should be avoided. That wording went into the file last December, when we last talked about this and everyone in that discussion agreed to remove the macro for the above reasons. Consistency matters. In this case, I don't think it does that much ... a cut and paste either way (from a macro or non-macro based driver) yields correct code. Since there's no bug here and no apparent way to misuse the macro, why bother? Anyway, it's PCI code ... let the PCI maintainer decide. However, if he does want this do it as one big bang patch via either the PCI or Trivial tree (latter because Jiří has experience doing this, but the former might be useful so the decider feels the pain ...) James ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
We have almost 1000 more uses of the non-macro version than the macro version in the kernel today: $ git grep -w DEFINE_PCI_DEVICE_TABLE | wc -l 262 $ git grep const struct pci_device_id | wc -l 1254 did you check for non-const ones? just to see if we have any of the broken case in the tree :-) as for consistency, pci_dev vs usb_device :-P Dave. ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH 0/25] Replace DEFINE_PCI_DEVICE_TABLE macro use
On Sat, Jul 19, 2014 at 07:14:12AM +1000, Dave Airlie wrote: We have almost 1000 more uses of the non-macro version than the macro version in the kernel today: $ git grep -w DEFINE_PCI_DEVICE_TABLE | wc -l 262 $ git grep const struct pci_device_id | wc -l 1254 did you check for non-const ones? just to see if we have any of the broken case in the tree :-) I didn't :) as for consistency, pci_dev vs usb_device :-P Read farther down the email... ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel