mirror_zfs/module/os/freebsd/zfs
Richard Yao 6a42939fcd
Cleanup: Address Clang's static analyzer's unused code complaints
These were categorized as the following:

 * Dead assignment		23
 * Dead increment		4
 * Dead initialization		6
 * Dead nested assignment	18

Most of these are harmless, but since actual issues can hide among them,
we correct them.

That said, there were a few return values that were being ignored that
appeared to merit some correction:

 * `destroy_callback()` in `cmd/zfs/zfs_main.c` ignored the error from
   `destroy_batched()`. We handle it by returning -1 if there is an
   error.

 * `zfs_do_upgrade()` in `cmd/zfs/zfs_main.c` ignored the error from
   `zfs_for_each()`. We handle it by doing a binary OR of the error
   value from the subsequent `zfs_for_each()` call to the existing
   value. This is how errors are mostly handled inside `zfs_for_each()`.
   The error value here is passed to exit from the zfs command, so doing
   a binary or on it is better than what we did previously.

 * `get_zap_prop()` in `module/zfs/zcp_get.c` ignored the error from
   `dsl_prop_get_ds()` when the property is not of type string. We
   return an error when it does. There is a small concern that the
   `zfs_get_temporary_prop()` call would handle things, but in the case
   that it does not, we would be pushing an uninitialized numval onto
   the lua stack. It is expected that `dsl_prop_get_ds()` will succeed
   anytime that `zfs_get_temporary_prop()` does, so that not giving it a
   chance to fix things is not a problem.

 * `draid_merge_impl()` in `tests/zfs-tests/cmd/draid.c` used
   `nvlist_add_nvlist()` twice in ways in which errors are expected to
   be impossible, so we switch to `fnvlist_add_nvlist()`.

A few notable ones did not merit use of the return value, so we
suppressed it with `(void)`:

 * `write_free_diffs()` in `lib/libzfs/libzfs_diff.c` ignored the error
   value from `describe_free()`. A look through the commit history
   revealed that this was intentional.

 * `arc_evict_hdr()` in `module/zfs/arc.c` did not need to use the
   returned handle from `arc_hdr_realloc()` because it is already
   referenced in lists.

 * `spa_vdev_detach()` in `module/zfs/spa.c` has a comment explicitly
   saying not to use the error from `vdev_label_init()` because whatever
   causes the error could be the reason why a detach is being done.

Unfortunately, I am not presently able to analyze the kernel modules
with Clang's static analyzer, so I could have missed some cases of this.
In cases where reports were present in code that is duplicated between
Linux and FreeBSD, I made a conscious effort to fix the FreeBSD version
too.

After this commit is merged, regressions like dee8934 should become
extremely obvious with Clang's static analyzer since a regression would
appear in the results as the only instance of unused code. That assumes
that Coverity does not catch the issue first.

My local branch with fixes from all of my outstanding non-draft pull
requests shows 118 reports from Clang's static anlayzer after this
patch. That is down by 51 from 169.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Cedric Berger <cedric@precidata.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13986
2022-10-14 13:37:54 -07:00
..
abd_os.c FreeBSD: use zero_region instead of allocating a dedicated page 2022-05-04 11:46:37 -07:00
arc_os.c Cleanup: Specify unsignedness on things that should not be signed 2022-09-27 16:42:41 -07:00
crypto_os.c FreeBSD: Improve crypto_dispatch() handling 2022-06-17 15:38:51 -07:00
dmu_os.c Remove bcopy(), bzero(), bcmp() 2022-03-15 15:13:42 -07:00
event_os.c FreeBSD: add knlist_init_sx() for exclusive locks 2022-09-06 09:48:57 -07:00
hkdf.c Remove bcopy(), bzero(), bcmp() 2022-03-15 15:13:42 -07:00
kmod_core.c FreeBSD: Replace legacy make_dev() interface usage 2022-09-08 10:40:18 -07:00
spa_os.c FreeBSD: Fix uninitialized pointer read in spa_import_rootpool() 2022-09-20 14:43:03 -07:00
sysctl_os.c Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
vdev_file.c Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
vdev_geom.c Improve too large physical ashift handling 2022-09-08 10:30:53 -07:00
vdev_label_os.c Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zfs_acl.c Add defensive assertions 2022-10-12 11:25:18 -07:00
zfs_ctldir.c FreeBSD: stop passing LK_INTERLOCK to VOP_LOCK 2022-09-19 17:17:27 -07:00
zfs_debug.c Cleanup: Specify unsignedness on things that should not be signed 2022-09-27 16:42:41 -07:00
zfs_dir.c FreeBSD: Cleanup zfs_readdir() 2022-09-20 14:50:16 -07:00
zfs_file_os.c FreeBSD: handle V_PCATCH 2022-09-20 15:22:32 -07:00
zfs_ioctl_compat.c FreeBSD compile fix 2022-07-28 14:19:41 -07:00
zfs_ioctl_os.c libzfs: On FreeBSD, use MNT_NOWAIT with getfsstat 2021-06-08 07:36:43 -06:00
zfs_racct.c module: zfs: fix unused, remove argsused 2021-12-23 09:42:47 -08:00
zfs_vfsops.c FreeBSD: Fix a pair of bugs in zfs_fhtovp() 2022-10-11 12:29:55 -07:00
zfs_vnops_os.c FreeBSD: catch up to 1400068 2022-09-20 15:21:30 -07:00
zfs_znode.c Cleanup: Address Clang's static analyzer's unused code complaints 2022-10-14 13:37:54 -07:00
zio_crypt.c Cleanup: Address Clang's static analyzer's unused code complaints 2022-10-14 13:37:54 -07:00
zvol_os.c FreeBSD: add kqfilter support for zvol cdev 2022-09-06 09:49:33 -07:00