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SubjectRe: [PATCH] CIFS: SMBD: work around gcc -Wmaybe-uninitialized warning
merged into cifs-2.6.git for-next

Also noticed a few sparse warnings in the same file that need to be cleaned up

On Wed, Jan 10, 2018 at 2:51 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> GCC versions from 4.9 to 6.3 produce a false-positive warning when
> dealing with a conditional spin_lock_irqsave():
>
> fs/cifs/smbdirect.c: In function 'smbd_recv_buf':
> include/linux/spinlock.h:260:3: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
>
> This function calls some sleeping interfaces, so it is clear that it
> does not get called with interrupts disabled and there is no need
> to save the irq state before taking the spinlock. This lets us
> remove the variable, which makes the function slightly more efficient
> and avoids the warning.
>
> A further cleanup could do the same change for other functions in this
> file, but I did not want to take this too far for now.
>
> Fixes: ac69f66e54ca ("CIFS: SMBD: Implement function to receive data via RDMA receive")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> fs/cifs/smbdirect.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
> index f527e22650f5..f9234ed83a60 100644
> --- a/fs/cifs/smbdirect.c
> +++ b/fs/cifs/smbdirect.c
> @@ -1862,7 +1862,6 @@ int smbd_recv_buf(struct smbd_connection *info, char *buf, unsigned int size)
> int to_copy, to_read, data_read, offset;
> u32 data_length, remaining_data_length, data_offset;
> int rc;
> - unsigned long flags;
>
> again:
> if (info->transport_status != SMBD_CONNECTED) {
> @@ -1935,15 +1934,13 @@ int smbd_recv_buf(struct smbd_connection *info, char *buf, unsigned int size)
> * end of the queue
> */
> if (!queue_length)
> - spin_lock_irqsave(
> - &info->reassembly_queue_lock,
> - flags);
> + spin_lock_irq(
> + &info->reassembly_queue_lock);
> list_del(&response->list);
> queue_removed++;
> if (!queue_length)
> - spin_unlock_irqrestore(
> - &info->reassembly_queue_lock,
> - flags);
> + spin_unlock_irq(
> + &info->reassembly_queue_lock);
>
> info->count_reassembly_queue--;
> info->count_dequeue_reassembly_queue++;
> @@ -1963,10 +1960,10 @@ int smbd_recv_buf(struct smbd_connection *info, char *buf, unsigned int size)
> to_read, data_read, offset);
> }
>
> - spin_lock_irqsave(&info->reassembly_queue_lock, flags);
> + spin_lock_irq(&info->reassembly_queue_lock);
> info->reassembly_data_length -= data_read;
> info->reassembly_queue_length -= queue_removed;
> - spin_unlock_irqrestore(&info->reassembly_queue_lock, flags);
> + spin_unlock_irq(&info->reassembly_queue_lock);
>
> info->first_entry_offset = offset;
> log_read(INFO, "returning to thread data_read=%d "
> --
> 2.9.0
>
> --
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--
Thanks,

Steve

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