bindinfo: lock before reading session ctx from BindHandle

[tangenta]

What problem does this PR solve?

Issue Number: close #42333

Problem Summary:

Read access:

tidb/bindinfo/handle.go

Lines 931 to 938 in a0e6ccb

	bindSQL := GenerateBindSQL(context.TODO(), stmt, bindableStmt.PlanHint, true, dbName)
	if bindSQL == "" {
	continue
	}
	charset, collation := h.sctx.GetSessionVars().GetCharsetInfo()
	binding := Binding{
	BindSQL: bindSQL,
	Status: Enabled,

Write access:

tidb/bindinfo/handle.go

Lines 216 to 227 in a0e6ccb

	h.bindInfo.Lock()
	h.sctx.Lock()
	defer func() {
	h.sctx.Unlock()
	h.bindInfo.Unlock()
	}()
	ctx := kv.WithInternalSourceType(context.Background(), kv.InternalTxnBindInfo)
	exec, _ := h.sctx.Context.(sqlexec.SQLExecutor)
	_, err = exec.ExecuteInternal(ctx, "BEGIN PESSIMISTIC")
	if err != nil {
	return
	}

We should lock for both read and write access of the field that being protected.

What is changed and how it works?

Omitted.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• wjhuang2016

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[hawkingrei]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: e2dde65

[hawkingrei]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #42956.