xen/libxc-sr-restore-pfns.patch

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From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 14:39:30 +0200
Subject: libxc sr restore pfns
tools: restore: preallocate pfns array
Remove repeated allocation from migration loop. There will never be
more than MAX_BATCH_SIZE pages to process in an incoming batch.
Allocate the space once.
Adjust the verification for page count. It must be at least one page,
but not more than MAX_BATCH_SIZE.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
tools/libs/guest/xg_sr_common.h | 1 +
tools/libs/guest/xg_sr_restore.c | 23 +++++++++++++++--------
2 files changed, 16 insertions(+), 8 deletions(-)
--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -256,6 +256,7 @@ struct xc_sr_context
{
struct xc_sr_restore_ops ops;
struct restore_callbacks *callbacks;
+ xen_pfn_t *pfns;
int send_back_fd;
unsigned long p2m_size;
--- a/tools/libs/guest/xg_sr_restore.c
+++ b/tools/libs/guest/xg_sr_restore.c
@@ -314,7 +314,7 @@ static int handle_page_data(struct xc_sr
unsigned int i, pages_of_data = 0;
int rc = -1;
- xen_pfn_t *pfns = NULL, pfn;
+ xen_pfn_t pfn;
uint32_t *types = NULL, type;
/*
@@ -349,9 +349,9 @@ static int handle_page_data(struct xc_sr
goto err;
}
- if ( pages->count < 1 )
+ if ( !pages->count || pages->count > MAX_BATCH_SIZE )
{
- ERROR("Expected at least 1 pfn in PAGE_DATA record");
+ ERROR("Unexpected pfn count %u in PAGE_DATA record", pages->count);
goto err;
}
@@ -362,9 +362,8 @@ static int handle_page_data(struct xc_sr
goto err;
}
- pfns = malloc(pages->count * sizeof(*pfns));
types = malloc(pages->count * sizeof(*types));
- if ( !pfns || !types )
+ if ( !types )
{
ERROR("Unable to allocate enough memory for %u pfns",
pages->count);
@@ -393,7 +392,7 @@ static int handle_page_data(struct xc_sr
* have a page worth of data in the record. */
pages_of_data++;
- pfns[i] = pfn;
+ ctx->restore.pfns[i] = pfn;
types[i] = type;
}
@@ -407,11 +406,10 @@ static int handle_page_data(struct xc_sr
goto err;
}
- rc = process_page_data(ctx, pages->count, pfns, types,
+ rc = process_page_data(ctx, pages->count, ctx->restore.pfns, types,
&pages->pfn[pages->count]);
err:
free(types);
- free(pfns);
return rc;
}
@@ -715,6 +713,14 @@ static int setup(struct xc_sr_context *c
goto err;
}
+ ctx->restore.pfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.pfns));
+ if ( !ctx->restore.pfns )
+ {
+ ERROR("Unable to allocate memory");
+ rc = -1;
+ goto err;
+ }
+
ctx->restore.buffered_records = malloc(
DEFAULT_BUF_RECORDS * sizeof(struct xc_sr_record));
if ( !ctx->restore.buffered_records )
@@ -745,6 +751,7 @@ static void cleanup(struct xc_sr_context
free(ctx->restore.buffered_records);
free(ctx->restore.populated_pfns);
+ free(ctx->restore.pfns);
if ( ctx->restore.ops.cleanup(ctx) )
PERROR("Failed to clean up");