This change introduce 2 items:
1. If the size of the space requested is 0, the behavior is implementation-defined:
either a null pointer shall be returned, or the behavior shall be as if the size
were some non-zero value, except that the behavior is undefined if the returned
pointer is used to access an object.
Change the behavior to be similar to Linux and Android and allocates an object
of a minimum size instead of returning null pointer.
https://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.htmlhttps://pubs.opengroup.org/onlinepubs/9699919799/functions/calloc.htmlhttps://pubs.opengroup.org/onlinepubs/9699919799/functions/realloc.html
2. The description of realloc() has been modified from previous versions of this
standard to align with the ISO/IEC 9899:1999 standard. Previous versions explicitly
permitted a call to realloc (p, 0) to free the space pointed to by p and return
a null pointer. While this behavior could be interpreted as permitted by this
version of the standard, the C language committee have indicated that this
interpretation is incorrect. Applications should assume that if realloc() returns
a null pointer, the space pointed to by p has not been freed. Since this could lead
to double-frees, implementations should also set errno if a null pointer actually
indicates a failure, and applications should only free the space if errno was changed.
Do not free memory of zero-length reallocation is requested
https://pubs.opengroup.org/onlinepubs/9699919799/functions/realloc.html
Co-authored-by: fangxinyong <fangxinyong@xiaomi.com>
Signed-off-by: Petro Karashchenko <petro.karashchenko@gmail.com>
There are many small memory block in NuttX system, eg: struct tcb_s,
struct inode, etc, and several disadvantages about them:
1.Their frequent allocate and free cause the system memory fragmentation.
2.Since each memory block has an overhead, the utilization of small memory
blocks is relatively low, which will cause memory waste.
So we can use mempool to alloc smallo block, to improve alloc speed
and utilization, to reduce fragmentation.
Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
The return value of function mm_takesemaphore will never below
than zero, DEBUGVERIFY make no effect to check it, use DEBUGASSERT
instead.
Signed-off-by: xiangdong6 <xiangdong6@xiaomi.com>
usage:
echo <pid/used/free> trace > /proc/memdump
echo used > /proc/memdump //output all used memory info with backtrace
echo free > /proc/memdump //output all free memory info
echo 22 > /proc/memdump //output used memory info for task pid is 22 with backtrace
Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>
1.Move all special process to mm_takesemaphore
2.Remove the support of recurive lock
3.Remove mm_trysemaphore function
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: Ie216a6294ab67c5d427f31b089beb15c532f08fe
When realloc up from a mem area to a larger one where a new node
is needed. The the larger memory region is copied from the source
this can both leak data as well as cause memory faults accesssing
invalid data.
This was first reported by Kwonsk
Signed-off-by: Brennan Ashton <bashton@brennanashton.com>
