2018-08-03 06:41:04

by Yue Haibing

Subject: [PATCH] um: NULL check before kfree is not needed

kfree(NULL) is safe,so this removes NULL check before freeing the mem

Signed-off-by: YueHaibing <[email protected]>
---
arch/um/drivers/vector_kern.c | 15 +++++----------
arch/um/drivers/vector_user.c | 6 ++----
arch/um/kernel/irq.c | 3 +--
3 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 50ee3bb..c84133c 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -1118,16 +1118,11 @@ static int vector_net_close(struct net_device *dev)
os_close_file(vp->fds->tx_fd);
vp->fds->tx_fd = -1;
}
- if (vp->bpf != NULL)
- kfree(vp->bpf);
- if (vp->fds->remote_addr != NULL)
- kfree(vp->fds->remote_addr);
- if (vp->transport_data != NULL)
- kfree(vp->transport_data);
- if (vp->header_rxbuffer != NULL)
- kfree(vp->header_rxbuffer);
- if (vp->header_txbuffer != NULL)
- kfree(vp->header_txbuffer);
+ kfree(vp->bpf);
+ kfree(vp->fds->remote_addr);
+ kfree(vp->transport_data);
+ kfree(vp->header_rxbuffer);
+ kfree(vp->header_txbuffer);
if (vp->rx_queue != NULL)
destroy_queue(vp->rx_queue);
if (vp->tx_queue != NULL)
diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index 4d6a78e..3d8cdbd 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -267,8 +267,7 @@ static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
os_close_file(rxfd);
if (txfd >= 0)
os_close_file(txfd);
- if (result != NULL)
- kfree(result);
+ kfree(result);
return NULL;
}

@@ -434,8 +433,7 @@ static struct vector_fds *user_init_socket_fds(struct arglist *ifspec, int id)
if (fd >= 0)
os_close_file(fd);
if (result != NULL) {
- if (result->remote_addr != NULL)
- kfree(result->remote_addr);
+ kfree(result->remote_addr);
kfree(result);
}
return NULL;
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index 6b7f382..8360fa3 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -244,8 +244,7 @@ static void garbage_collect_irq_entries(void)
to_free = NULL;
}
walk = walk->next;
- if (to_free != NULL)
- kfree(to_free);
+ kfree(to_free);
}
}

--
2.7.0

2018-08-04 16:43:33

by Anton Ivanov

Subject: Re: [PATCH] um: NULL check before kfree is not needed

On 03/08/18 07:39, YueHaibing wrote:

> kfree(NULL) is safe,so this removes NULL check before freeing the mem
>
> Signed-off-by: YueHaibing <[email protected]>
> ---
> arch/um/drivers/vector_kern.c | 15 +++++----------
> arch/um/drivers/vector_user.c | 6 ++----
> arch/um/kernel/irq.c | 3 +--
> 3 files changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
> index 50ee3bb..c84133c 100644
> --- a/arch/um/drivers/vector_kern.c
> +++ b/arch/um/drivers/vector_kern.c
> @@ -1118,16 +1118,11 @@ static int vector_net_close(struct net_device *dev)
> os_close_file(vp->fds->tx_fd);
> vp->fds->tx_fd = -1;
> }
> - if (vp->bpf != NULL)
> - kfree(vp->bpf);
> - if (vp->fds->remote_addr != NULL)
> - kfree(vp->fds->remote_addr);
> - if (vp->transport_data != NULL)
> - kfree(vp->transport_data);
> - if (vp->header_rxbuffer != NULL)
> - kfree(vp->header_rxbuffer);
> - if (vp->header_txbuffer != NULL)
> - kfree(vp->header_txbuffer);
> + kfree(vp->bpf);
> + kfree(vp->fds->remote_addr);
> + kfree(vp->transport_data);
> + kfree(vp->header_rxbuffer);
> + kfree(vp->header_txbuffer);
> if (vp->rx_queue != NULL)
> destroy_queue(vp->rx_queue);
> if (vp->tx_queue != NULL)
> diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
> index 4d6a78e..3d8cdbd 100644
> --- a/arch/um/drivers/vector_user.c
> +++ b/arch/um/drivers/vector_user.c
> @@ -267,8 +267,7 @@ static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
> os_close_file(rxfd);
> if (txfd >= 0)
> os_close_file(txfd);
> - if (result != NULL)
> - kfree(result);
> + kfree(result);
> return NULL;
> }
>
> @@ -434,8 +433,7 @@ static struct vector_fds *user_init_socket_fds(struct arglist *ifspec, int id)
> if (fd >= 0)
> os_close_file(fd);
> if (result != NULL) {
> - if (result->remote_addr != NULL)
> - kfree(result->remote_addr);
> + kfree(result->remote_addr);
> kfree(result);
> }
> return NULL;
> diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
> index 6b7f382..8360fa3 100644
> --- a/arch/um/kernel/irq.c
> +++ b/arch/um/kernel/irq.c
> @@ -244,8 +244,7 @@ static void garbage_collect_irq_entries(void)
> to_free = NULL;
> }
> walk = walk->next;
> - if (to_free != NULL)
> - kfree(to_free);
> + kfree(to_free);
> }
> }
>
kfree in both slab and slob check for NULLs before freeing so this is
correct. Thanks for noticing.

Richard, please apply,

A.