On Tue, 11 Jun 2024 14:40:29 +0000
Wei Yang <richard.weiy...@gmail.com> wrote:
Missed this just before sending out v3 :-p
> >diff --git a/mm/memblock.c b/mm/memblock.c
> >index d09136e040d3..a8bf0ee9e2b4 100644
> >--- a/mm/memblock.c
> >+++ b/mm/memblock.c
> >@@ -2244,6 +2244,103 @@ void __init memblock_free_all(void)
> > totalram_pages_add(pages);
> > }
> >
> >+/* Keep a table to reserve named memory */
> >+#define RESERVE_MEM_MAX_ENTRIES 8
> >+#define RESERVE_MEM_NAME_SIZE 16
> ^
> Suggest to align with previous line.
It is. But because the patch adds a "+", it pushed the "8" out another tab.
>
> >+struct reserve_mem_table {
> >+ char name[RESERVE_MEM_NAME_SIZE];
> >+ unsigned long start;
> >+ unsigned long size;
>
> phys_addr_t looks more precise?
For just the start variable, correct? I'm OK with updating that.
>
> >+};
> >+static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES];
> >+static int reserved_mem_count;
>
> Seems no matter we use this feature or not, these memory would be occupied?
Yes, because allocation may screw it up as well. I could add a CONFIG
around it, so that those that do not want this could configure it out. But
since it's just a total of (16 + 8 + 8) * 8 = 256 bytes, I'm not sure it's
much of a worry to add the complexities to save that much space. As the
code to save it may likely be bigger.
>
> >+
> >+/* Add wildcard region with a lookup name */
> >+static int __init reserved_mem_add(unsigned long start, unsigned long size,
> >+ const char *name)
> >+{
> >+ struct reserve_mem_table *map;
> >+
> >+ if (!name || !name[0] || strlen(name) >= RESERVE_MEM_NAME_SIZE)
> >+ return -EINVAL;
> >+
> >+ if (reserved_mem_count >= RESERVE_MEM_MAX_ENTRIES)
> >+ return -1;
>
> return ENOSPC? Not good at it, but a raw value maybe not a good practice.
This is what gets returned by the command line parser. It only cares if it
is zero or not.
>
> Also, we'd better do this check before allocation.
What allocation?
>
> >+
> >+ map = &reserved_mem_table[reserved_mem_count++];
> >+ map->start = start;
> >+ map->size = size;
> >+ strscpy(map->name, name);
> >+ return 0;
> >+}
> >+
> >+/**
> >+ * reserve_mem_find_by_name - Find reserved memory region with a given name
> >+ * @name: The name that is attached to a reserved memory region
> >+ * @start: If found, holds the start address
> >+ * @size: If found, holds the size of the address.
> >+ *
> >+ * Returns: 1 if found or 0 if not found.
> >+ */
> >+int reserve_mem_find_by_name(const char *name, unsigned long *start,
> >unsigned long *size)
> >+{
> >+ struct reserve_mem_table *map;
> >+ int i;
> >+
> >+ for (i = 0; i < reserved_mem_count; i++) {
> >+ map = &reserved_mem_table[i];
> >+ if (!map->size)
> >+ continue;
> >+ if (strcmp(name, map->name) == 0) {
> >+ *start = map->start;
> >+ *size = map->size;
> >+ return 1;
> >+ }
> >+ }
> >+ return 0;
> >+}
> >+
> >+/*
> >+ * Parse early_reserve_mem=nn:align:name
>
> early_reserve_mem or reserve_mem ?
Oops, that was the original name. I'll change that.
>
> >+ */
> >+static int __init reserve_mem(char *p)
> >+{
> >+ phys_addr_t start, size, align;
Hmm, I wonder if I should change size and align to unsigned long?
> >+ char *oldp;
> >+ int err;
> >+
> >+ if (!p)
> >+ return -EINVAL;
> >+
> >+ oldp = p;
> >+ size = memparse(p, &p);
> >+ if (p == oldp)
> >+ return -EINVAL;
> >+
> >+ if (*p != ':')
> >+ return -EINVAL;
> >+
> >+ align = memparse(p+1, &p);
> >+ if (*p != ':')
> >+ return -EINVAL;
> >+
>
> Better to check if the name is valid here.
You mean that it has text and is not blank?
>
> Make sure command line parameters are valid before doing the allocation.
You mean that size is non zero?
I don't know if we care what the align is. Zero is valid.
>
> >+ start = memblock_phys_alloc(size, align);
> >+ if (!start)
> >+ return -ENOMEM;
> >+
> >+ p++;
> >+ err = reserved_mem_add(start, size, p);
> >+ if (err) {
> >+ memblock_phys_free(start, size);
> >+ return err;
> >+ }
> >+
> >+ p += strlen(p);
> >+
> >+ return *p == '\0' ? 0: -EINVAL;
>
> We won't free the memory if return -EINVAL?
I guess we can do this check before the allocation, like you suggested.
Thanks for the review.
-- Steve
>
> >+}
> >+__setup("reserve_mem=", reserve_mem);
> >+
> > #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK)
> > static const char * const flagname[] = {
> > [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
> >--
> >2.43.0
> >
> >
>
