* Mahmoud Mandour (ma.mandourr@gmail.com) wrote:
> Replaced the calls to malloc()/calloc() and their respective
> calls to free() of iovec structs with GLib's allocation and
> deallocation functions.
>
> Also, in one instance, used g_new0() instead of a calloc() call plus
> a null-checking assertion.
>
> iovec structs were created locally and freed as the function
> ends. Hence, I used g_autofree and removed the respective calls to
> free().
>
> In one instance, a struct fuse_ioctl_iovec pointer is returned from a
> function, namely, fuse_ioctl_iovec_copy. There, I used g_steal_pointer()
> in conjunction with g_autofree, this gives the ownership of the pointer
> to the calling function and still auto-frees the memory when the calling
> function finishes (maintaining the symantics of previous code).
>
> Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> tools/virtiofsd/fuse_lowlevel.c | 19 +++++++------------
> tools/virtiofsd/fuse_virtio.c | 6 +-----
> 2 files changed, 8 insertions(+), 17 deletions(-)
>
> diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
> index 812cef6ef6..f965299ad9 100644
> --- a/tools/virtiofsd/fuse_lowlevel.c
> +++ b/tools/virtiofsd/fuse_lowlevel.c
> @@ -217,9 +217,9 @@ static int send_reply(fuse_req_t req, int error, const void *arg,
> int fuse_reply_iov(fuse_req_t req, const struct iovec *iov, int count)
> {
> int res;
> - struct iovec *padded_iov;
> + g_autofree struct iovec *padded_iov;
>
> - padded_iov = malloc((count + 1) * sizeof(struct iovec));
> + padded_iov = g_try_new(struct iovec, count + 1);
> if (padded_iov == NULL) {
> return fuse_reply_err(req, ENOMEM);
> }
> @@ -228,7 +228,6 @@ int fuse_reply_iov(fuse_req_t req, const struct iovec *iov, int count)
> count++;
>
> res = send_reply_iov(req, 0, padded_iov, count);
> - free(padded_iov);
>
> return res;
> }
OK.
> @@ -565,10 +564,10 @@ int fuse_reply_bmap(fuse_req_t req, uint64_t idx)
> static struct fuse_ioctl_iovec *fuse_ioctl_iovec_copy(const struct iovec *iov,
> size_t count)
> {
> - struct fuse_ioctl_iovec *fiov;
> + g_autofree struct fuse_ioctl_iovec *fiov;
> size_t i;
>
> - fiov = malloc(sizeof(fiov[0]) * count);
> + fiov = g_try_new(fuse_ioctl_iovec, count);
> if (!fiov) {
> return NULL;
> }
> @@ -578,7 +577,7 @@ static struct fuse_ioctl_iovec *fuse_ioctl_iovec_copy(const struct iovec *iov,
> fiov[i].len = iov[i].iov_len;
> }
>
> - return fiov;
> + return g_steal_pointer(&fiov);
> }
This is OK, but doesn't gain anything - marking it as g_autofree'ing and
always stealing is no benefit.
>
> int fuse_reply_ioctl_retry(fuse_req_t req, const struct iovec *in_iov,
> @@ -629,9 +628,6 @@ int fuse_reply_ioctl_retry(fuse_req_t req, const struct iovec *in_iov,
>
> res = send_reply_iov(req, 0, iov, count);
> out:
> - free(in_fiov);
> - free(out_fiov);
> -
I don't think you can do that - I think you're relying here on the
g_autofree from fuse_ioclt_iovec_copy - but my understanding is that
doesn't work; g_autofree is scoped, so it's designed to free at the end
of fuse_ioctl_iovec_copy, fuse_reply_ioctl_retry doesn't know that the
ion_fiov were allocated that way, so it won't get autocleaned up.
In GLib's documentation, it is clarified (w.r.t. g_autoptr but I think similar logic applies to g_autofree)
that g_steal_pointer() "This can be very useful when combined with g_autoptr() to prevent
the return value of a function from being automatically freed."
I think, but not 100% clear of course, that this means that the g_autoptr-annotated memory
does not get freed at the end of the current scope, and its "scope" is migrated to the calling
function(to be honest I don't know how would they implement that but maybe this is the case).
Otherwise why bother with g_autoptr'ing memory that we don't want to free automatically and
would like to return to the calling function?
the memory as g_autoptr and then returns it through g_steal_pointer. With your logic, I think that
this example would be wrong(?)
in a previous version and this v2 patch series is supposed to only contain already-reviewed patches and
remove bad ones
> return res;
>
> enomem:
> @@ -663,11 +659,11 @@ int fuse_reply_ioctl(fuse_req_t req, int result, const void *buf, size_t size)
> int fuse_reply_ioctl_iov(fuse_req_t req, int result, const struct iovec *iov,
> int count)
> {
> - struct iovec *padded_iov;
> + g_autofree struct iovec *padded_iov;
> struct fuse_ioctl_out arg;
> int res;
>
> - padded_iov = malloc((count + 2) * sizeof(struct iovec));
> + padded_iov = g_try_new(struct iovec, count + 2);
> if (padded_iov == NULL) {
> return fuse_reply_err(req, ENOMEM);
> }
> @@ -680,7 +676,6 @@ int fuse_reply_ioctl_iov(fuse_req_t req, int result, const struct iovec *iov,
> memcpy(&padded_iov[2], iov, count * sizeof(struct iovec));
>
> res = send_reply_iov(req, 0, padded_iov, count + 2);
> - free(padded_iov);
>
> return res;
> }
OK
> diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
> index 3e13997406..07e5d91a9f 100644
> --- a/tools/virtiofsd/fuse_virtio.c
> +++ b/tools/virtiofsd/fuse_virtio.c
> @@ -347,8 +347,7 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
> * Build a copy of the the in_sg iov so we can skip bits in it,
> * including changing the offsets
> */
> - struct iovec *in_sg_cpy = calloc(sizeof(struct iovec), in_num);
> - assert(in_sg_cpy);
> + g_autofree struct iovec *in_sg_cpy = g_new0(struct iovec, in_num);
> memcpy(in_sg_cpy, in_sg, sizeof(struct iovec) * in_num);
> /* These get updated as we skip */
> struct iovec *in_sg_ptr = in_sg_cpy;
> @@ -386,7 +385,6 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
> ret = errno;
> fuse_log(FUSE_LOG_DEBUG, "%s: preadv failed (%m) len=%zd\n",
> __func__, len);
> - free(in_sg_cpy);
> goto err;
> }
> fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
> @@ -410,13 +408,11 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
> if (ret != len) {
> fuse_log(FUSE_LOG_DEBUG, "%s: ret!=len\n", __func__);
> ret = EIO;
> - free(in_sg_cpy);
> goto err;
> }
> in_sg_left -= ret;
> len -= ret;
> } while (in_sg_left);
> - free(in_sg_cpy);
Yes, this is where the autofree really helps; getting rid of a few
free's.
Dave
> /* Need to fix out->len on EOF */
> if (len) {
> --
> 2.25.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Thanks,
Mahmoud