Messages in this thread Patch in this message | | | Date | Thu, 16 Oct 2008 13:40:56 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 02/46] sysfs: crash debugging |
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* Greg Kroah-Hartman (gregkh@suse.de) wrote: > From: Andrew Morton <akpm@linux-foundation.org> > > Print the name of the last-accessed sysfs file when we oops, to help track > down oopses which occur in sysfs store/read handlers. Because these oopses > tend to not leave any trace of the offending code in the stack traces. > > Cc: Kay Sievers <kay.sievers@vrfy.org> > Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> > --- > arch/x86/kernel/dumpstack_32.c | 2 ++ > arch/x86/kernel/dumpstack_64.c | 2 ++ > fs/sysfs/file.c | 13 +++++++++++++ > include/linux/sysfs.h | 6 ++++++ > 4 files changed, 23 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c > index 201ee35..1a78180 100644 > --- a/arch/x86/kernel/dumpstack_32.c > +++ b/arch/x86/kernel/dumpstack_32.c > @@ -13,6 +13,7 @@ > #include <linux/kexec.h> > #include <linux/bug.h> > #include <linux/nmi.h> > +#include <linux/sysfs.h> > > #include <asm/stacktrace.h> > > @@ -343,6 +344,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err) > printk("DEBUG_PAGEALLOC"); > #endif > printk("\n"); > + sysfs_printk_last_file(); > if (notify_die(DIE_OOPS, str, regs, err, > current->thread.trap_no, SIGSEGV) == NOTIFY_STOP) > return 1; > diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c > index 086cc81..96a5db7 100644 > --- a/arch/x86/kernel/dumpstack_64.c > +++ b/arch/x86/kernel/dumpstack_64.c > @@ -13,6 +13,7 @@ > #include <linux/kexec.h> > #include <linux/bug.h> > #include <linux/nmi.h> > +#include <linux/sysfs.h> > > #include <asm/stacktrace.h> > > @@ -489,6 +490,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err) > printk("DEBUG_PAGEALLOC"); > #endif > printk("\n"); > + sysfs_printk_last_file(); > if (notify_die(DIE_OOPS, str, regs, err, > current->thread.trap_no, SIGSEGV) == NOTIFY_STOP) > return 1; > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c > index c9e4e50..ce8339c 100644 > --- a/fs/sysfs/file.c > +++ b/fs/sysfs/file.c > @@ -19,10 +19,18 @@ > #include <linux/poll.h> > #include <linux/list.h> > #include <linux/mutex.h> > +#include <linux/limits.h> > #include <asm/uaccess.h> > > #include "sysfs.h" > > +/* used in crash dumps to help with debugging */ > +static char last_sysfs_file[PATH_MAX]; > +void sysfs_printk_last_file(void) > +{ > + printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file); > +} > + > /* > * There's one sysfs_buffer for each open file and one > * sysfs_open_dirent for each sysfs_dirent with one or more open > @@ -328,6 +336,11 @@ static int sysfs_open_file(struct inode *inode, struct file *file) > struct sysfs_buffer *buffer; > struct sysfs_ops *ops; > int error = -EACCES; > + char *p; > + > + p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file)); > + if (p)
if (!IS_ERR(p)) ?
> + memmove(last_sysfs_file, p, strlen(p) + 1); >
Given we do a strlen() here anyway, shouldn't we just use strcpy ?
Mathieu
> /* need attr_sd for attr and ops, its parent for kobj */ > if (!sysfs_get_active_two(attr_sd)) > diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h > index 37fa241..8ec406a 100644 > --- a/include/linux/sysfs.h > +++ b/include/linux/sysfs.h > @@ -119,6 +119,8 @@ void sysfs_remove_file_from_group(struct kobject *kobj, > > void sysfs_notify(struct kobject *kobj, char *dir, char *attr); > > +void sysfs_printk_last_file(void); > + > extern int __must_check sysfs_init(void); > > #else /* CONFIG_SYSFS */ > @@ -231,6 +233,10 @@ static inline int __must_check sysfs_init(void) > return 0; > } > > +static inline void sysfs_printk_last_file(void) > +{ > +} > + > #endif /* CONFIG_SYSFS */ > > #endif /* _SYSFS_H_ */ > -- > 1.6.0.2 >
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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