On Thu, Feb 07, 2008 at 04:10:52PM -0800, Stephen Hemminger wrote:
> Jason Baron <[EMAIL PROTECTED]> wrote:
>
> >
> > -add /proc/sys/debug/pr_debug, to toggle pr_debug() on/off
> >
> > Signed-off-by: Jason Baron <[EMAIL PROTECTED]>
> > ---
> >
> > kernel/sysctl.c | 41 +++++++++++++++++++++++++++++++++++++++++
> > 1 files changed, 41 insertions(+), 0 deletions(-)
> >
> >
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index 7cb1ac3..73508d7 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -155,6 +155,11 @@ static int proc_do_cad_pid(struct ctl_table *table,
> > int write, struct file *filp
> > static int proc_dointvec_taint(struct ctl_table *table, int write, struct
> > file *filp,
> > void __user *buffer, size_t *lenp, loff_t *ppos);
> > #endif
> > +#ifdef CONFIG_PR_DEBUG_DYNAMIC
> > +static int proc_pr_debug_handler(struct ctl_table *table, int write,
> > + struct file *filp, void __user *buffer,
> > + size_t *lenp, loff_t *ppos);
> > +#endif
> >
> > static struct ctl_table root_table[];
> > static struct ctl_table_root sysctl_table_root;
> > @@ -1312,6 +1317,16 @@ static struct ctl_table debug_table[] = {
> > .proc_handler = proc_dointvec
> > },
> > #endif
> > +#ifdef CONFIG_PR_DEBUG_DYNAMIC
> > + {
> > + .ctl_name = CTL_UNNUMBERED,
> > + .procname = "pr_debug",
> > + .data = NULL,
> > + .maxlen = sizeof(int),
> > + .mode = 0644,
> > + .proc_handler = &proc_pr_debug_handler
> > + },
> > +#endif
> > { .ctl_name = 0 }
> > };
> >
> > @@ -2499,6 +2514,32 @@ static int proc_do_cad_pid(struct ctl_table *table,
> > int write, struct file *filp
> > return 0;
> > }
> >
> > +#ifdef CONFIG_PR_DEBUG_DYNAMIC
> > +
> > +static int proc_pr_debug_handler(struct ctl_table *table, int write,
> > + struct file *filp, void __user *buffer,
> > + size_t *lenp, loff_t *ppos)
> > +{
> > + int tmp, r;
> > +
> > + if (!write)
> > + tmp = imv_read(pr_debug_on);
> > + r = __do_proc_dointvec(&tmp, table, write, filp, buffer,
> > + lenp, ppos, NULL, NULL);
> > + if (r)
> > + return r;
> > +
> > + if (write) {
> > + if (tmp)
> > + imv_set(pr_debug_on, 1);
> > + else
> > + imv_set(pr_debug_on, 0);
> > + }
> > + return 0;
> > +}
> > +
> > +#endif
> > +
> > #else /* CONFIG_PROC_FS */
> >
> > int proc_dostring(struct ctl_table *table, int write, struct file *filp,
>
> Please no, there are many pr_debug calls that are only intended for debugging
> that
> particular subsystem, not a global enable/disable. It also adds to kernel
> bloat.
>
Yes, but you are going to have to re-compile your kernel to get at them...the
ability to turn on/off pr_debug() calls, at runtime, seems like a powerful
runtime diagnostic tool...the CONFIG_PR_DEBUG_DYNAMIC can default to 'n',
instead of being automactically set as I've proposed. In terms of bloat, the
vmlinux file goes from 53649330 to 53985478, < %1 increase.
thanks,
-Jason
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