| Message ID | 20241211021703.2333-2-semen.protsenko@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | lmb: Fix reserving the same region multiple times | expand |
Thanks Sam! On Wed, 11 Dec 2024 at 04:17, Sam Protsenko <semen.protsenko@linaro.org> wrote: > > An attempt to add the already added LMB region using > lmb_add_region_flags() ends up in lmb_addrs_overlap() check, which > eventually leads to either returning 0 if 'flags' is LMB_NONE, or -1 > otherwise. It makes it impossible for the user of this function to catch > the case when the region is already added and differentiate it from > regular errors. That in turn may lead to incorrect error handling in the > caller code, like reporting misleading errors or interrupting the normal > code path where it could be treated as the normal case. An example is > boot_fdt_reserve_region() function, which might be called twice (e.g. > during board startup in initr_lmb(), and then during 'booti' command > booting the OS), thus trying to reserve exactly the same memory regions > described in the device tree twice, which produces an error message on > second call. > > Return -EEXIST error code in case when the added region exists and it's > not LMB_NONE; for LMB_NONE return 0, to conform to unit tests > (specifically test_alloc_addr() in test/lib/lmb.c) and the preferred > behavior described in commit 1d9aa4a283da ("lmb: Fix the allocation of > overlapping memory areas with !LMB_NONE"). The change of > lmb_add_region_flags() return values is described in the table below: > > Return case Pre-1d9 1d9 New > ----------------------------------------------------------- > Added successfully 0 0 0 > Failed to add -1 -1 -1 > Already added, flags == LMB_NONE 0 0 0 > Already added, flags != LMB_NONE 0 -1 -EEXIST > > Rework all affected functions and their documentation. Also fix the > corresponding unit test which checks reserving the same region with the > same flags to account for the changed return value. > > No functional change is intended (by this patch itself). > > Fixes: 1d9aa4a283da ("lmb: Fix the allocation of overlapping memory areas with !LMB_NONE") > Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > --- > Changes in v2: > - Removed the check for exactly the same region, and return -EEXIST in > the branch handling overlapping regions instead > - Reworded the commit message accordingly > > lib/lmb.c | 26 +++++++++++++------------- > test/lib/lmb.c | 2 +- > 2 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/lib/lmb.c b/lib/lmb.c > index b03237bc06cb..a695edf70dfa 100644 > --- a/lib/lmb.c > +++ b/lib/lmb.c > @@ -183,8 +183,10 @@ static long lmb_resize_regions(struct alist *lmb_rgn_lst, > * the function might resize an already existing region or coalesce two > * adjacent regions. > * > - * > - * Returns: 0 if the region addition successful, -1 on failure > + * Return: > + * * %0 - Added successfully, or it's already added (only if LMB_NONE) > + * * %-EEXIST - The region is already added, and flags != LMB_NONE > + * * %-1 - Failure > */ > static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base, > phys_size_t size, enum lmb_flags flags) > @@ -217,17 +219,15 @@ static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base, > coalesced++; > break; > } else if (lmb_addrs_overlap(base, size, rgnbase, rgnsize)) { > - if (flags == LMB_NONE) { > - ret = lmb_resize_regions(lmb_rgn_lst, i, base, > - size); > - if (ret < 0) > - return -1; > + if (flags != LMB_NONE) > + return -EEXIST; > > - coalesced++; > - break; > - } else { > + ret = lmb_resize_regions(lmb_rgn_lst, i, base, size); > + if (ret < 0) > return -1; > - } > + > + coalesced++; > + break; > } > } > > @@ -667,7 +667,7 @@ long lmb_add(phys_addr_t base, phys_size_t size) > * > * Free up a region of memory. > * > - * Return: 0 if successful, -1 on failure > + * Return: 0 if successful, negative error code on failure > */ > long lmb_free_flags(phys_addr_t base, phys_size_t size, > uint flags) > @@ -818,7 +818,7 @@ static phys_addr_t _lmb_alloc_addr(phys_addr_t base, phys_size_t size, > lmb_memory[rgn].size, > base + size - 1, 1)) { > /* ok, reserve the memory */ > - if (lmb_reserve_flags(base, size, flags) >= 0) > + if (!lmb_reserve_flags(base, size, flags)) > return base; > } > } > diff --git a/test/lib/lmb.c b/test/lib/lmb.c > index 0bd29e2a4fe7..48c3c966f8f2 100644 > --- a/test/lib/lmb.c > +++ b/test/lib/lmb.c > @@ -754,7 +754,7 @@ static int lib_test_lmb_flags(struct unit_test_state *uts) > > /* reserve again, same flag */ > ret = lmb_reserve_flags(0x40010000, 0x10000, LMB_NOMAP); > - ut_asserteq(ret, -1L); > + ut_asserteq(ret, -EEXIST); > ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000, > 0, 0, 0, 0); > > -- > 2.39.5 > Tom this needs to go in -master for the release Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/lmb.c b/lib/lmb.c index b03237bc06cb..a695edf70dfa 100644 --- a/lib/lmb.c +++ b/lib/lmb.c @@ -183,8 +183,10 @@ static long lmb_resize_regions(struct alist *lmb_rgn_lst, * the function might resize an already existing region or coalesce two * adjacent regions. * - * - * Returns: 0 if the region addition successful, -1 on failure + * Return: + * * %0 - Added successfully, or it's already added (only if LMB_NONE) + * * %-EEXIST - The region is already added, and flags != LMB_NONE + * * %-1 - Failure */ static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base, phys_size_t size, enum lmb_flags flags) @@ -217,17 +219,15 @@ static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base, coalesced++; break; } else if (lmb_addrs_overlap(base, size, rgnbase, rgnsize)) { - if (flags == LMB_NONE) { - ret = lmb_resize_regions(lmb_rgn_lst, i, base, - size); - if (ret < 0) - return -1; + if (flags != LMB_NONE) + return -EEXIST; - coalesced++; - break; - } else { + ret = lmb_resize_regions(lmb_rgn_lst, i, base, size); + if (ret < 0) return -1; - } + + coalesced++; + break; } } @@ -667,7 +667,7 @@ long lmb_add(phys_addr_t base, phys_size_t size) * * Free up a region of memory. * - * Return: 0 if successful, -1 on failure + * Return: 0 if successful, negative error code on failure */ long lmb_free_flags(phys_addr_t base, phys_size_t size, uint flags) @@ -818,7 +818,7 @@ static phys_addr_t _lmb_alloc_addr(phys_addr_t base, phys_size_t size, lmb_memory[rgn].size, base + size - 1, 1)) { /* ok, reserve the memory */ - if (lmb_reserve_flags(base, size, flags) >= 0) + if (!lmb_reserve_flags(base, size, flags)) return base; } } diff --git a/test/lib/lmb.c b/test/lib/lmb.c index 0bd29e2a4fe7..48c3c966f8f2 100644 --- a/test/lib/lmb.c +++ b/test/lib/lmb.c @@ -754,7 +754,7 @@ static int lib_test_lmb_flags(struct unit_test_state *uts) /* reserve again, same flag */ ret = lmb_reserve_flags(0x40010000, 0x10000, LMB_NOMAP); - ut_asserteq(ret, -1L); + ut_asserteq(ret, -EEXIST); ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000, 0, 0, 0, 0);
An attempt to add the already added LMB region using lmb_add_region_flags() ends up in lmb_addrs_overlap() check, which eventually leads to either returning 0 if 'flags' is LMB_NONE, or -1 otherwise. It makes it impossible for the user of this function to catch the case when the region is already added and differentiate it from regular errors. That in turn may lead to incorrect error handling in the caller code, like reporting misleading errors or interrupting the normal code path where it could be treated as the normal case. An example is boot_fdt_reserve_region() function, which might be called twice (e.g. during board startup in initr_lmb(), and then during 'booti' command booting the OS), thus trying to reserve exactly the same memory regions described in the device tree twice, which produces an error message on second call. Return -EEXIST error code in case when the added region exists and it's not LMB_NONE; for LMB_NONE return 0, to conform to unit tests (specifically test_alloc_addr() in test/lib/lmb.c) and the preferred behavior described in commit 1d9aa4a283da ("lmb: Fix the allocation of overlapping memory areas with !LMB_NONE"). The change of lmb_add_region_flags() return values is described in the table below: Return case Pre-1d9 1d9 New ----------------------------------------------------------- Added successfully 0 0 0 Failed to add -1 -1 -1 Already added, flags == LMB_NONE 0 0 0 Already added, flags != LMB_NONE 0 -1 -EEXIST Rework all affected functions and their documentation. Also fix the corresponding unit test which checks reserving the same region with the same flags to account for the changed return value. No functional change is intended (by this patch itself). Fixes: 1d9aa4a283da ("lmb: Fix the allocation of overlapping memory areas with !LMB_NONE") Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> --- Changes in v2: - Removed the check for exactly the same region, and return -EEXIST in the branch handling overlapping regions instead - Reworded the commit message accordingly lib/lmb.c | 26 +++++++++++++------------- test/lib/lmb.c | 2 +- 2 files changed, 14 insertions(+), 14 deletions(-)