| Message ID | 20190913220300.422869-5-andrealmeid@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | null_blk: fixes around nr_devices and log improvements | expand |
I'm not super familier with the format, will let someone do the final review. In general looks good. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> On 09/13/2019 03:04 PM, André Almeida wrote: > The pr_fmt macro is useful to format log messages printed by pr_XXXX() > functions. Add text to explain the purpose of it, how to use and an > example. > > Signed-off-by: André Almeida<andrealmeid@collabora.com> > Cc: Jonathan Corbet<corbet@lwn.net> > --- > Changes from v1: > - Add Jonathan as explict Cc > - Replace "include/printk.h" by "#include <linux/kernel.h> > - Add note about #undef > - Replace hardcore string by KBUILD_MODNAME at the example > ---
On Fri, 13 Sep 2019 19:03:00 -0300 André Almeida <andrealmeid@collabora.com> wrote: > The pr_fmt macro is useful to format log messages printed by pr_XXXX() > functions. Add text to explain the purpose of it, how to use and an > example. So I've finally had a chance to take a real look at this... > diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst > index f4a2198187f9..1a33a933fbd3 100644 > --- a/Documentation/process/coding-style.rst > +++ b/Documentation/process/coding-style.rst > @@ -819,7 +819,15 @@ which you should use to make sure messages are matched to the right device > and driver, and are tagged with the right level: dev_err(), dev_warn(), > dev_info(), and so forth. For messages that aren't associated with a > particular device, <linux/printk.h> defines pr_notice(), pr_info(), > -pr_warn(), pr_err(), etc. > +pr_warn(), pr_err(), etc. It's possible to format pr_XXX() messages using the > +macro pr_fmt() to prevent rewriting the style of messages. It should be > +defined before ``#include <linux/kernel.h>``, to avoid compiler warning about > +redefinitions, or just use ``#undef pr_fmt``. This is particularly useful for > +adding the name of the module at the beginning of the message, for instance: > + > +.. code-block:: c > + > + #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Honestly, I think that this is out of scope for a document on coding style. That document is already far too long for most people to read, I don't think we should load it down with more stuff that isn't directly style related. That said, the information can be useful. I wanted to say that it should go with the documentation of the pr_* macros but ... well ... um ... we don't seem to have a whole lot of that. Figures. I suspect this is more than you wanted to sign up for, but...IMO, the right thing to do is to fill printk.h with a nice set of kerneldoc comments describing how this stuff should be used, then to pull that information into the core-api manual, somewhere near our extensive discussion of printk formats. It's amazing that we lack docs for something so basic. Thanks, jon
On 9/14/19 4:50 AM, Jonathan Corbet wrote: > On Fri, 13 Sep 2019 19:03:00 -0300 > André Almeida <andrealmeid@collabora.com> wrote: > >> The pr_fmt macro is useful to format log messages printed by pr_XXXX() >> functions. Add text to explain the purpose of it, how to use and an >> example. > > So I've finally had a chance to take a real look at this... > >> diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst >> index f4a2198187f9..1a33a933fbd3 100644 >> --- a/Documentation/process/coding-style.rst >> +++ b/Documentation/process/coding-style.rst >> @@ -819,7 +819,15 @@ which you should use to make sure messages are matched to the right device >> and driver, and are tagged with the right level: dev_err(), dev_warn(), >> dev_info(), and so forth. For messages that aren't associated with a >> particular device, <linux/printk.h> defines pr_notice(), pr_info(), >> -pr_warn(), pr_err(), etc. >> +pr_warn(), pr_err(), etc. It's possible to format pr_XXX() messages using the >> +macro pr_fmt() to prevent rewriting the style of messages. It should be >> +defined before ``#include <linux/kernel.h>``, to avoid compiler warning about >> +redefinitions, or just use ``#undef pr_fmt``. This is particularly useful for >> +adding the name of the module at the beginning of the message, for instance: >> + >> +.. code-block:: c >> + >> + #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > Honestly, I think that this is out of scope for a document on coding > style. That document is already far too long for most people to read, I > don't think we should load it down with more stuff that isn't directly > style related. > > That said, the information can be useful. I wanted to say that it should > go with the documentation of the pr_* macros but ... well ... um ... we > don't seem to have a whole lot of that. Figures. > > I suspect this is more than you wanted to sign up for, but...IMO, the right > thing to do is to fill printk.h with a nice set of kerneldoc comments > describing how this stuff should be used, then to pull that information > into the core-api manual, somewhere near our extensive discussion of printk > formats. It's amazing that we lack docs for something so basic. > Thanks for the feedback jon. For now, I'll drop this patch for this series. In a future patch I'll move this text for Documentation/core-api/printk-formats.rst and will also add kernel-doc comments to pr_XXXX() functions. > Thanks, > > jon >
diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst index f4a2198187f9..1a33a933fbd3 100644 --- a/Documentation/process/coding-style.rst +++ b/Documentation/process/coding-style.rst @@ -819,7 +819,15 @@ which you should use to make sure messages are matched to the right device and driver, and are tagged with the right level: dev_err(), dev_warn(), dev_info(), and so forth. For messages that aren't associated with a particular device, <linux/printk.h> defines pr_notice(), pr_info(), -pr_warn(), pr_err(), etc. +pr_warn(), pr_err(), etc. It's possible to format pr_XXX() messages using the +macro pr_fmt() to prevent rewriting the style of messages. It should be +defined before ``#include <linux/kernel.h>``, to avoid compiler warning about +redefinitions, or just use ``#undef pr_fmt``. This is particularly useful for +adding the name of the module at the beginning of the message, for instance: + +.. code-block:: c + + #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Coming up with good debugging messages can be quite a challenge; and once you have them, they can be a huge help for remote troubleshooting. However
The pr_fmt macro is useful to format log messages printed by pr_XXXX() functions. Add text to explain the purpose of it, how to use and an example. Signed-off-by: André Almeida <andrealmeid@collabora.com> Cc: Jonathan Corbet <corbet@lwn.net> --- Changes from v1: - Add Jonathan as explict Cc - Replace "include/printk.h" by "#include <linux/kernel.h> - Add note about #undef - Replace hardcore string by KBUILD_MODNAME at the example --- Documentation/process/coding-style.rst | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)