This patch broke gitlab-ci:
https://gitlab.com/xen-project/people/sstabellini/xen/-/jobs/1684530258
In file included from guest_4.c:2:
./multi.c:2159:9: error: unused variable 'r' [-Werror,-Wunused-variable]
int r;
^
1 error generated.
make[5]: *** [/builds/xen-project/people/sstabellini/xen/xen/Rules.mk:197:
guest_4.o] Error 1
To be sure I got the right commit, I confirmed that by reverting the
commit gitlab-ci passes again:
https://gitlab.com/xen-project/people/sstabellini/xen/-/pipelines/389383466
On Wed, 13 Oct 2021, Jan Beulich wrote:
> Coverity dislikes sh_page_fault() storing the return value into a local
> variable but then never using the value (and oddly enough spots this in
> the 2- and 3-level cases, but not in the 4-level one). Instead of adding
> yet another cast to void as replacement, take the opportunity and drop a
> bunch of such casts at the same time - not using function return values
> is a common thing to do. (It of course is an independent question
> whether ignoring errors like this is a good idea.)
>
> Coverity-ID: 1492856
> Coverity-ID: 1492858
> Signed-off-by: Jan Beulich <[email protected]>
>
> --- a/xen/arch/x86/mm/shadow/multi.c
> +++ b/xen/arch/x86/mm/shadow/multi.c
> @@ -1416,7 +1416,7 @@ void sh_unhook_32b_mappings(struct domai
> shadow_l2e_t *sl2e;
> SHADOW_FOREACH_L2E(sl2mfn, sl2e, 0, 0, d, {
> if ( !user_only || (sl2e->l2 & _PAGE_USER) )
> - (void) shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> + shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> });
> }
>
> @@ -1428,7 +1428,7 @@ void sh_unhook_pae_mappings(struct domai
> shadow_l2e_t *sl2e;
> SHADOW_FOREACH_L2E(sl2mfn, sl2e, 0, 0, d, {
> if ( !user_only || (sl2e->l2 & _PAGE_USER) )
> - (void) shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> + shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> });
> }
>
> @@ -1439,7 +1439,7 @@ void sh_unhook_64b_mappings(struct domai
> shadow_l4e_t *sl4e;
> SHADOW_FOREACH_L4E(sl4mfn, sl4e, 0, 0, d, {
> if ( !user_only || (sl4e->l4 & _PAGE_USER) )
> - (void) shadow_set_l4e(d, sl4e, shadow_l4e_empty(), sl4mfn);
> + shadow_set_l4e(d, sl4e, shadow_l4e_empty(), sl4mfn);
> });
> }
>
> @@ -1969,7 +1969,7 @@ static void sh_prefetch(struct vcpu *v,
>
> /* Propagate the entry. */
> l1e_propagate_from_guest(v, gl1e, gmfn, &sl1e, ft_prefetch, p2mt);
> - (void) shadow_set_l1e(d, ptr_sl1e + i, sl1e, p2mt, sl1mfn);
> + shadow_set_l1e(d, ptr_sl1e + i, sl1e, p2mt, sl1mfn);
>
> #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
> if ( snpl1p != NULL )
> @@ -2534,7 +2534,7 @@ static int sh_page_fault(struct vcpu *v,
>
> /* Calculate the shadow entry and write it */
> l1e_propagate_from_guest(v, gw.l1e, gmfn, &sl1e, ft, p2mt);
> - r = shadow_set_l1e(d, ptr_sl1e, sl1e, p2mt, sl1mfn);
> + shadow_set_l1e(d, ptr_sl1e, sl1e, p2mt, sl1mfn);
>
> #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
> if ( mfn_valid(gw.l1mfn)
> @@ -3014,8 +3014,7 @@ static bool sh_invlpg(struct vcpu *v, un
> shadow_l1e_t *sl1;
> sl1 = sh_linear_l1_table(v) +
> shadow_l1_linear_offset(linear);
> /* Remove the shadow entry that maps this VA */
> - (void) shadow_set_l1e(d, sl1, shadow_l1e_empty(),
> - p2m_invalid, sl1mfn);
> + shadow_set_l1e(d, sl1, shadow_l1e_empty(), p2m_invalid,
> sl1mfn);
> }
> paging_unlock(d);
> /* Need the invlpg, to pick up the disappeareance of the sl1e */
> @@ -3608,7 +3607,8 @@ int sh_rm_write_access_from_l1(struct do
> && (mfn_x(shadow_l1e_get_mfn(*sl1e)) == mfn_x(readonly_mfn)) )
> {
> shadow_l1e_t ro_sl1e = shadow_l1e_remove_flags(*sl1e, _PAGE_RW);
> - (void) shadow_set_l1e(d, sl1e, ro_sl1e, p2m_ram_rw, sl1mfn);
> +
> + shadow_set_l1e(d, sl1e, ro_sl1e, p2m_ram_rw, sl1mfn);
> #if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
> /* Remember the last shadow that we shot a writeable mapping in
> */
> if ( curr->domain == d )
> @@ -3637,8 +3637,7 @@ int sh_rm_mappings_from_l1(struct domain
> if ( (flags & _PAGE_PRESENT)
> && (mfn_x(shadow_l1e_get_mfn(*sl1e)) == mfn_x(target_mfn)) )
> {
> - (void) shadow_set_l1e(d, sl1e, shadow_l1e_empty(),
> - p2m_invalid, sl1mfn);
> + shadow_set_l1e(d, sl1e, shadow_l1e_empty(), p2m_invalid, sl1mfn);
> if ( sh_check_page_has_no_refs(mfn_to_page(target_mfn)) )
> /* This breaks us cleanly out of the FOREACH macro */
> done = 1;
> @@ -3656,20 +3655,20 @@ void sh_clear_shadow_entry(struct domain
> switch ( mfn_to_page(smfn)->u.sh.type )
> {
> case SH_type_l1_shadow:
> - (void) shadow_set_l1e(d, ep, shadow_l1e_empty(), p2m_invalid, smfn);
> + shadow_set_l1e(d, ep, shadow_l1e_empty(), p2m_invalid, smfn);
> break;
> case SH_type_l2_shadow:
> #if GUEST_PAGING_LEVELS >= 4
> case SH_type_l2h_shadow:
> #endif
> - (void) shadow_set_l2e(d, ep, shadow_l2e_empty(), smfn);
> + shadow_set_l2e(d, ep, shadow_l2e_empty(), smfn);
> break;
> #if GUEST_PAGING_LEVELS >= 4
> case SH_type_l3_shadow:
> - (void) shadow_set_l3e(d, ep, shadow_l3e_empty(), smfn);
> + shadow_set_l3e(d, ep, shadow_l3e_empty(), smfn);
> break;
> case SH_type_l4_shadow:
> - (void) shadow_set_l4e(d, ep, shadow_l4e_empty(), smfn);
> + shadow_set_l4e(d, ep, shadow_l4e_empty(), smfn);
> break;
> #endif
> default: BUG(); /* Called with the wrong kind of shadow. */
> @@ -3689,7 +3688,7 @@ int sh_remove_l1_shadow(struct domain *d
> if ( (flags & _PAGE_PRESENT)
> && (mfn_x(shadow_l2e_get_mfn(*sl2e)) == mfn_x(sl1mfn)) )
> {
> - (void) shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> + shadow_set_l2e(d, sl2e, shadow_l2e_empty(), sl2mfn);
> if ( mfn_to_page(sl1mfn)->u.sh.type == 0 )
> /* This breaks us cleanly out of the FOREACH macro */
> done = 1;
> @@ -3712,7 +3711,7 @@ int sh_remove_l2_shadow(struct domain *d
> if ( (flags & _PAGE_PRESENT)
> && (mfn_x(shadow_l3e_get_mfn(*sl3e)) == mfn_x(sl2mfn)) )
> {
> - (void) shadow_set_l3e(d, sl3e, shadow_l3e_empty(), sl3mfn);
> + shadow_set_l3e(d, sl3e, shadow_l3e_empty(), sl3mfn);
> if ( mfn_to_page(sl2mfn)->u.sh.type == 0 )
> /* This breaks us cleanly out of the FOREACH macro */
> done = 1;
> @@ -3734,7 +3733,7 @@ int sh_remove_l3_shadow(struct domain *d
> if ( (flags & _PAGE_PRESENT)
> && (mfn_x(shadow_l4e_get_mfn(*sl4e)) == mfn_x(sl3mfn)) )
> {
> - (void) shadow_set_l4e(d, sl4e, shadow_l4e_empty(), sl4mfn);
> + shadow_set_l4e(d, sl4e, shadow_l4e_empty(), sl4mfn);
> if ( mfn_to_page(sl3mfn)->u.sh.type == 0 )
> /* This breaks us cleanly out of the FOREACH macro */
> done = 1;
>
>
