cpu/atmega_common: wrappers for memory management function to avoid preemption#11998
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maribu merged 2 commits intoRIOT-OS:masterfrom Aug 13, 2019
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gschorcht
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Area: cpu
Memory management function like `malloc`, `calloc`, `realloc` and `free` must not be preempted when they operate on allocator structures. To avoid such a preemption, wrappers around these functions are used which simply disable all interrupts for the time of their execution.
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is this related to #8619? |
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Not really. PR #8619 implements the locking mechanism as used by |
maribu
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Reviewed: 1-fundamentals
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OK, for testing I modified Detailsdiff --git a/examples/hello-world/main.c b/examples/hello-world/main.c
index f51bf8c0a0..212e0f62f4 100644
--- a/examples/hello-world/main.c
+++ b/examples/hello-world/main.c
@@ -20,6 +20,7 @@
*/
#include <stdio.h>
+#include <stdlib.h>
int main(void)
{
@@ -27,6 +28,14 @@ int main(void)
printf("You are running RIOT on a(n) %s board.\n", RIOT_BOARD);
printf("This board features a(n) %s MCU.\n", RIOT_MCU);
+ void *a = malloc(4);
+ printf("void *a = %p\n", a);
+ void *b = calloc(4, 4);
+ printf("void *b = %p\n", b);
+ a = realloc(a, 32);
+ printf("void *a = %p (after realloc)\n", a);
+ free(a);
+ free(b);
return 0;
}The console output was DetailsSo no regressions were introduced. Finally, I disassembled the symbol main and got the following output: DetailsSo every call to |
maribu
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ACK. Thanks for this very elegant fix!
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@maribu Thanks for reviewing, testing and merging. |
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Contribution description
This PR is an aproach to fix the problem described in #10842.
Memory management function like
malloc,calloc,reallocandfreemust not be preempted when they operate on allocator structures. To avoid such a preemption, wrappers around these functions are used which simply disable all interrupts for the time of their execution.This approach produces 78 additional bytes of code.
Testing procedure
Flash and run
tests/malloc.Issues/PRs references
Fixes #10842