On 3/23/2015 10:52 PM, Pavel Boldin wrote:
On Mon, Mar 23, 2015 at 4:41 PM, Xie, Huawei <huawei.xie at intel.com<mailto:huawei.xie at intel.com>> wrote: On 3/23/2015 10:37 PM, Pavel Boldin wrote: On Mon, Mar 23, 2015 at 4:21 PM, Xie, Huawei <huawei.xie at intel.com<mailto:huawei.xie at intel.com><mailto:huawei.xie at intel.com<mailto:huawei.xie at intel.com>>> wrote: On 3/23/2015 8:54 PM, Pavel Boldin wrote: > Due to increased `struct file's reference counter subsequent call > to `filp_close' does not free the `struct file'. Prepend `fput' call > to decrease the reference counter. > > Signed-off-by: Pavel Boldin <pboldin at mirantis.com<mailto:pboldin at > mirantis.com><mailto:pboldin at mirantis.com<mailto:pboldin at mirantis.com>>> > --- > lib/librte_vhost/eventfd_link/eventfd_link.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c > b/lib/librte_vhost/eventfd_link/eventfd_link.c > index 7755dd6..62c45c8 100644 > --- a/lib/librte_vhost/eventfd_link/eventfd_link.c > +++ b/lib/librte_vhost/eventfd_link/eventfd_link.c > @@ -117,6 +117,7 @@ eventfd_link_ioctl(struct file *f, unsigned int ioctl, > unsigned long arg) > * Release the existing eventfd in the source process > */ > spin_lock(&files->file_lock); > + fput(file); Could we just call atomic_long_dec here? We can but I don't like breaking encapsulation (which is broken anyway by the code). So, there is a special method and we should use it in my opinion. it is increased by atomic_long_inc_not_zero so why don't we use the symmetric function? The code with `atomic_long_inc_not_zero' call is a copy-paste of the `fget' function. If we want to make it clear we should make a separate function and name it so: `fget_from_files'. I don't understand why there is a (exact?) copy&paste of fget there. :). Maybe you could post a patchset, first replace the copy/paste with fget and then this patch. It will looks much clearer. Second thing is: another thread of the same processor can call the `sys_close' on the `fd' and this will dereference counter so `fput' will correctly free the `struct file'. Using `atomic_long_dec' will leak a `struct file' and print a KERN_ERR message by `filp_close'. So, the common thing is to use appropriate functions and don't reinvent the wheel. Pavel Pavel > filp_close(file, files); > fdt = files_fdtable(files); > fdt->fd[eventfd_copy.source_fd] = NULL;
