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
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freebsd	Cleanup: Address Clang's static analyzer's unused code complaints	2022-10-14 13:37:54 -07:00
linux	Cleanup: Address Clang's static analyzer's unused code complaints	2022-10-14 13:37:54 -07:00