[PATCH v2 1/6] lmb: check if a region can be reserved by lmb_reserve()
Heinrich Schuchardt
heinrich.schuchardt at canonical.com
Thu Feb 20 11:28:11 CET 2025
On 20.02.25 10:56, Sughosh Ganu wrote:
> The logic used in lmb_alloc() takes into consideration the existing
> reserved regions, and ensures that the allocated region does not
> overlap with any existing allocated regions. The lmb_reserve()
> function is not doing any such checks -- the requested region might
> overlap with an existing region. This also shows up with
> lmb_alloc_addr() as this function ends up calling lmb_reserve().
>
> Add a function which checks if the region requested is overlapping
> with an existing reserved region, and allow for the reservation to
> happen only if both the regions have LMB_NONE flag, which allows
> re-requesting of the region. In any other scenario of an overlap, have
> lmb_reserve() return -EEXIST, implying that the requested region is
> already reserved.
>
> Add corresponding test cases which check for overlapping reservation
> requests made through lmb_reserve() and lmb_alloc_addr(). And while
> here, fix some of the comments in the test function being touched.
>
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
Looks good to me.
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
> Changes since V1:
> * Add documentation for the lmb_can_reserve_region() function.
> * Add an additional test case where a new region is being added, and
> the new region overlaps two different existing regions, with
> mismatching flags.
> * Some cleanup of comments in the lib_test_lmb_overlapping_reserve()
> function.
>
> lib/lmb.c | 36 ++++++++++++++++
> test/lib/lmb.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 146 insertions(+), 4 deletions(-)
>
> diff --git a/lib/lmb.c b/lib/lmb.c
> index 7ca44591e1d..d7d2c8c6dfd 100644
> --- a/lib/lmb.c
> +++ b/lib/lmb.c
> @@ -595,6 +595,39 @@ static __maybe_unused void lmb_reserve_common_spl(void)
> }
> }
>
> +/**
> + * lmb_can_reserve_region() - check if the region can be reserved
> + * @base: base address of region to be reserved
> + * @size: size of region to be reserved
> + * @flags: flag of the region to be reserved
> + *
> + * Go through all the reserved regions and ensure that the requested
> + * region does not overlap with any existing regions. An overlap is
> + * allowed only when the flag of the request region and the existing
> + * region is LMB_NONE.
> + *
> + * Return: true if region can be reserved, false otherwise
> + */
> +static bool lmb_can_reserve_region(phys_addr_t base, phys_size_t size,
> + u32 flags)
> +{
> + uint i;
> + struct lmb_region *lmb_reserved = lmb.used_mem.data;
> +
> + for (i = 0; i < lmb.used_mem.count; i++) {
> + u32 rgnflags = lmb_reserved[i].flags;
> + phys_addr_t rgnbase = lmb_reserved[i].base;
> + phys_size_t rgnsize = lmb_reserved[i].size;
> +
> + if (lmb_addrs_overlap(base, size, rgnbase, rgnsize)) {
> + if (flags != LMB_NONE || flags != rgnflags)
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
> void lmb_add_memory(void)
> {
> int i;
> @@ -667,6 +700,9 @@ long lmb_reserve(phys_addr_t base, phys_size_t size, u32 flags)
> long ret = 0;
> struct alist *lmb_rgn_lst = &lmb.used_mem;
>
> + if (!lmb_can_reserve_region(base, size, flags))
> + return -EEXIST;
> +
> ret = lmb_add_region_flags(lmb_rgn_lst, base, size, flags);
> if (ret)
> return ret;
> diff --git a/test/lib/lmb.c b/test/lib/lmb.c
> index fcb5f1af532..24416e83491 100644
> --- a/test/lib/lmb.c
> +++ b/test/lib/lmb.c
> @@ -471,17 +471,17 @@ static int lib_test_lmb_overlapping_reserve(struct unit_test_state *uts)
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000,
> 0, 0, 0, 0);
>
> - /* allocate overlapping region should return the coalesced count */
> + /* allocate overlapping region */
> ret = lmb_reserve(0x40011000, 0x10000, LMB_NONE);
> ut_asserteq(ret, 0);
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x11000,
> 0, 0, 0, 0);
> - /* allocate 3nd region */
> + /* allocate 2nd region */
> ret = lmb_reserve(0x40030000, 0x10000, LMB_NONE);
> ut_asserteq(ret, 0);
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40010000, 0x11000,
> 0x40030000, 0x10000, 0, 0);
> - /* allocate 2nd region , This should coalesced all region into one */
> + /* allocate 3rd region , This should coalesce all regions into one */
> ret = lmb_reserve(0x40020000, 0x10000, LMB_NONE);
> ut_assert(ret >= 0);
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x30000,
> @@ -499,6 +499,41 @@ static int lib_test_lmb_overlapping_reserve(struct unit_test_state *uts)
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40000000, 0x40000,
> 0, 0, 0, 0);
>
> + /* try to allocate overlapping region with a different flag, should fail */
> + ret = lmb_reserve(0x40008000, 0x1000, LMB_NOOVERWRITE);
> + ut_asserteq(ret, -EEXIST);
> +
> + /* allocate another region at 0x40050000 with a different flag */
> + ret = lmb_reserve(0x40050000, 0x10000, LMB_NOOVERWRITE);
> + ut_asserteq(ret, 0);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x40000,
> + 0x40050000, 0x10000, 0, 0);
> +
> + /*
> + * try to reserve a region adjacent to region 1 overlapping the 2nd region,
> + * should fail
> + */
> + ret = lmb_reserve(0x40040000, 0x20000, LMB_NONE);
> + ut_asserteq(ret, -EEXIST);
> +
> + /*
> + * try to reserve a region between the two regions, but without an overlap,
> + * should succeed. this added region coalesces with the region 1
> + */
> + ret = lmb_reserve(0x40040000, 0x10000, LMB_NONE);
> + ut_asserteq(ret, 0);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x50000,
> + 0x40050000, 0x10000, 0, 0);
> +
> + /*
> + * try to reserve a region which overlaps with both the regions,
> + * should fail as the flags do not match
> + */
> + ret = lmb_reserve(0x40020000, 0x80000, LMB_NONE);
> + ut_asserteq(ret, -EEXIST);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x50000,
> + 0x40050000, 0x10000, 0, 0);
> +
> lmb_pop(&store);
>
> return 0;
> @@ -549,6 +584,77 @@ static int test_alloc_addr(struct unit_test_state *uts, const phys_addr_t ram)
> ret = lmb_free(alloc_addr_a, 0x1000);
> ut_asserteq(ret, 0);
>
> + /*
> + * Add two regions with different flags, region1 and region2 with
> + * a gap between them.
> + * Try adding another region, adjacent to region 1 and overlapping
> + * region 2. Should fail.
> + */
> + a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NONE);
> + ut_asserteq(a, alloc_addr_a);
> +
> + b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NOOVERWRITE);
> + ut_asserteq(b, alloc_addr_a + 0x4000);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
> + b, 0x1000, 0, 0);
> +
> + c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NONE);
> + ut_asserteq(c, 0);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
> + b, 0x1000, 0, 0);
> +
> + ret = lmb_free(a, 0x1000);
> + ut_asserteq(ret, 0);
> + ret = lmb_free(b, 0x1000);
> + ut_asserteq(ret, 0);
> +
> + /*
> + * Add two regions with same flags(LMB_NONE), region1 and region2
> + * with a gap between them.
> + * Try adding another region, adjacent to region 1 and overlapping
> + * region 2. Should succeed. All regions should coalesce into a
> + * single region.
> + */
> + a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NONE);
> + ut_asserteq(a, alloc_addr_a);
> +
> + b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NONE);
> + ut_asserteq(b, alloc_addr_a + 0x4000);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
> + b, 0x1000, 0, 0);
> +
> + c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NONE);
> + ut_asserteq(c, alloc_addr_a + 0x1000);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, a, 0x6000,
> + 0, 0, 0, 0);
> +
> + ret = lmb_free(a, 0x6000);
> + ut_asserteq(ret, 0);
> +
> + /*
> + * Add two regions with same flags(LMB_NOOVERWRITE), region1 and
> + * region2 with a gap between them.
> + * Try adding another region, adjacent to region 1 and overlapping
> + * region 2. Should fail.
> + */
> + a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NOOVERWRITE);
> + ut_asserteq(a, alloc_addr_a);
> +
> + b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NOOVERWRITE);
> + ut_asserteq(b, alloc_addr_a + 0x4000);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
> + b, 0x1000, 0, 0);
> +
> + c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NOOVERWRITE);
> + ut_asserteq(c, 0);
> + ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
> + b, 0x1000, 0, 0);
> +
> + ret = lmb_free(a, 0x1000);
> + ut_asserteq(ret, 0);
> + ret = lmb_free(b, 0x1000);
> + ut_asserteq(ret, 0);
> +
> /* reserve 3 blocks */
> ret = lmb_reserve(alloc_addr_a, 0x10000, LMB_NONE);
> ut_asserteq(ret, 0);
> @@ -760,7 +866,7 @@ static int lib_test_lmb_flags(struct unit_test_state *uts)
>
> /* reserve again, new flag */
> ret = lmb_reserve(0x40010000, 0x10000, LMB_NONE);
> - ut_asserteq(ret, -1);
> + ut_asserteq(ret, -EEXIST);
> ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000,
> 0, 0, 0, 0);
>
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