Messages in this thread | | | Date | Thu, 3 Jun 2010 09:41:58 +0200 | Subject | Re: [RFC 4/5] BKL: use no BKL in llseek | From | Geert Uytterhoeven <> |
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On Thu, Jun 3, 2010 at 02:13, Arnd Bergmann <arnd@arndb.de> wrote: > We have shown that the BKL in default_llseek and other > llseek operations never protects against concurrent access > from another function:
> --- a/drivers/zorro/proc.c > +++ b/drivers/zorro/proc.c > @@ -23,7 +23,7 @@ proc_bus_zorro_lseek(struct file *file, loff_t off, int whence) > { > loff_t new = -1; > > - lock_kernel(); > + mutex_lock(&file->f_dentry->d_inode->i_mutex); > switch (whence) { > case 0: > new = off; > @@ -36,10 +36,10 @@ proc_bus_zorro_lseek(struct file *file, loff_t off, int whence) > break; > } > if (new < 0 || new > sizeof(struct ConfigDev)) { > - unlock_kernel(); > + mutex_unlock(&file->f_dentry->d_inode->i_mutex); > return -EINVAL; > } > - unlock_kernel(); > + mutex_unlock(&file->f_dentry->d_inode->i_mutex); > return (file->f_pos = new); > }
I was about to fix this like drivers/pci/proc.c handles it (origiginally I cloned it from that fil anyway). Compared to your version, that also moves the setting of file->f_pos inside the mutex, which is probably also needed in other places...
> --- a/drivers/pnp/isapnp/proc.c > +++ b/drivers/pnp/isapnp/proc.c > @@ -32,7 +32,7 @@ static loff_t isapnp_proc_bus_lseek(struct file *file, loff_t off, int whence) > { > loff_t new = -1; > > - lock_kernel(); > + mutex_lock(&file->f_dentry->d_inode->i_mutex); > switch (whence) { > case 0: > new = off; > @@ -45,10 +45,10 @@ static loff_t isapnp_proc_bus_lseek(struct file *file, loff_t off, int whence) > break; > } > if (new < 0 || new > 256) { > - unlock_kernel(); > + mutex_unlock(&file->f_dentry->d_inode->i_mutex); > return -EINVAL; > } > - unlock_kernel(); > + mutex_unlock(&file->f_dentry->d_inode->i_mutex); > return (file->f_pos = new);
... like here?
> }
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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