[edk2-devel] [PATCH 05/11] OvmfPkg/XenBusDxe: Construct paths without allocation
Anthony PERARD
anthony.perard at citrix.com
Fri Sep 13 14:50:54 UTC 2019
When doing an action with a path and subpath in the xenstore,
XenStoreJoin is called to generate "$path/$subpath". But this function
do an allocation of memory which isn't necessary. Instead we will
construct the path with WRITE_REQUEST and data used to generate the
path will be copied directly to the xenstore shared ring.
Also change WRITE_REQUEST.Len type, it only contain sizes and doesn't
need to be exactly 32bits.
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2190
Signed-off-by: Anthony PERARD <anthony.perard at citrix.com>
---
OvmfPkg/XenBusDxe/XenStore.c | 78 +++++++++++++++++++++---------------
1 file changed, 46 insertions(+), 32 deletions(-)
diff --git a/OvmfPkg/XenBusDxe/XenStore.c b/OvmfPkg/XenBusDxe/XenStore.c
index 7b71dc156d..ca7be12d68 100644
--- a/OvmfPkg/XenBusDxe/XenStore.c
+++ b/OvmfPkg/XenBusDxe/XenStore.c
@@ -53,7 +53,7 @@
typedef struct {
CONST VOID *Data;
- UINT32 Len;
+ UINTN Len;
} WRITE_REQUEST;
/* Register callback to watch subtree (node) in the XenStore. */
@@ -260,6 +260,35 @@ XenStoreFindWatch (
return NULL;
}
+/**
+ Fill the first three slots of a WRITE_REQUEST array.
+
+ When those three slots are concatenated to generate a string, the resulting
+ string will be "$Path\0" or "$Path/$SubPath\0" if SubPath is provided.
+**/
+STATIC
+VOID
+XenStorePrepareWriteRequest (
+ IN OUT WRITE_REQUEST *WriteRequest,
+ IN CONST CHAR8 *Path,
+ IN CONST CHAR8 *SubPath OPTIONAL
+ )
+{
+ SetMem(WriteRequest, 3 * sizeof (WRITE_REQUEST), 0);
+ WriteRequest[0].Data = Path;
+ WriteRequest[0].Len = AsciiStrSize (Path);
+ if (SubPath != NULL && SubPath[0] != '\0') {
+ //
+ // Remove the \0 from the first part of the request.
+ //
+ WriteRequest[0].Len--;
+ WriteRequest[1].Data = "/";
+ WriteRequest[1].Len = 1;
+ WriteRequest[2].Data = SubPath;
+ WriteRequest[2].Len = AsciiStrSize (SubPath);
+ }
+}
+
//
// Public Utility Functions
// API comments for these methods can be found in XenStore.h
@@ -842,6 +871,7 @@ XenStoreTalkv (
@param Transaction The transaction to use for this request.
@param RequestType The type of message to send.
@param Body The body of the request.
+ @param SubPath If !NULL and not "", "/$SubPath" is append to Body.
@param LenPtr The returned length of the reply.
@param Result The returned body of the reply.
@@ -854,16 +884,16 @@ XenStoreSingle (
IN CONST XENSTORE_TRANSACTION *Transaction,
IN enum xsd_sockmsg_type RequestType,
IN CONST CHAR8 *Body,
+ IN CONST CHAR8 *SubPath OPTIONAL,
OUT UINT32 *LenPtr OPTIONAL,
OUT VOID **Result OPTIONAL
)
{
- WRITE_REQUEST WriteRequest;
+ WRITE_REQUEST WriteRequest[3];
- WriteRequest.Data = (VOID *) Body;
- WriteRequest.Len = (UINT32)AsciiStrSize (Body);
+ XenStorePrepareWriteRequest (WriteRequest, Body, SubPath);
- return XenStoreTalkv (Transaction, RequestType, &WriteRequest, 1,
+ return XenStoreTalkv (Transaction, RequestType, WriteRequest, 3,
LenPtr, Result);
}
@@ -1113,15 +1143,12 @@ XenStoreListDirectory (
OUT CONST CHAR8 ***DirectoryListPtr
)
{
- CHAR8 *Path;
CHAR8 *TempStr;
UINT32 Len = 0;
XENSTORE_STATUS Status;
- Path = XenStoreJoin (DirectoryPath, Node);
- Status = XenStoreSingle (Transaction, XS_DIRECTORY, Path, &Len,
+ Status = XenStoreSingle (Transaction, XS_DIRECTORY, DirectoryPath, Node, &Len,
(VOID **) &TempStr);
- FreePool (Path);
if (Status != XENSTORE_STATUS_SUCCESS) {
return Status;
}
@@ -1160,13 +1187,11 @@ XenStoreRead (
OUT VOID **Result
)
{
- CHAR8 *Path;
VOID *Value;
XENSTORE_STATUS Status;
- Path = XenStoreJoin (DirectoryPath, Node);
- Status = XenStoreSingle (Transaction, XS_READ, Path, LenPtr, &Value);
- FreePool (Path);
+ Status = XenStoreSingle (Transaction, XS_READ, DirectoryPath, Node,
+ LenPtr, &Value);
if (Status != XENSTORE_STATUS_SUCCESS) {
return Status;
}
@@ -1183,21 +1208,13 @@ XenStoreWrite (
IN CONST CHAR8 *Str
)
{
- CHAR8 *Path;
- WRITE_REQUEST WriteRequest[2];
- XENSTORE_STATUS Status;
+ WRITE_REQUEST WriteRequest[4];
- Path = XenStoreJoin (DirectoryPath, Node);
+ XenStorePrepareWriteRequest (WriteRequest, DirectoryPath, Node);
+ WriteRequest[3].Data = Str;
+ WriteRequest[3].Len = AsciiStrLen (Str);
- WriteRequest[0].Data = (VOID *) Path;
- WriteRequest[0].Len = (UINT32)AsciiStrSize (Path);
- WriteRequest[1].Data = (VOID *) Str;
- WriteRequest[1].Len = (UINT32)AsciiStrLen (Str);
-
- Status = XenStoreTalkv (Transaction, XS_WRITE, WriteRequest, 2, NULL, NULL);
- FreePool (Path);
-
- return Status;
+ return XenStoreTalkv (Transaction, XS_WRITE, WriteRequest, 4, NULL, NULL);
}
XENSTORE_STATUS
@@ -1207,12 +1224,9 @@ XenStoreRemove (
IN CONST CHAR8 *Node
)
{
- CHAR8 *Path;
XENSTORE_STATUS Status;
- Path = XenStoreJoin (DirectoryPath, Node);
- Status = XenStoreSingle (Transaction, XS_RM, Path, NULL, NULL);
- FreePool (Path);
+ Status = XenStoreSingle (Transaction, XS_RM, DirectoryPath, Node, NULL, NULL);
return Status;
}
@@ -1226,7 +1240,7 @@ XenStoreTransactionStart (
XENSTORE_STATUS Status;
Status = XenStoreSingle (XST_NIL, XS_TRANSACTION_START, "", NULL,
- (VOID **) &IdStr);
+ NULL, (VOID **) &IdStr);
if (Status == XENSTORE_STATUS_SUCCESS) {
Transaction->Id = (UINT32)AsciiStrDecimalToUintn (IdStr);
FreePool (IdStr);
@@ -1246,7 +1260,7 @@ XenStoreTransactionEnd (
AbortStr[0] = Abort ? 'F' : 'T';
AbortStr[1] = '\0';
- return XenStoreSingle (Transaction, XS_TRANSACTION_END, AbortStr, NULL, NULL);
+ return XenStoreSingle (Transaction, XS_TRANSACTION_END, AbortStr, NULL, NULL, NULL);
}
XENSTORE_STATUS
--
Anthony PERARD
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