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charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::32b; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x32b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1667222666797100001 We originally naively treated expansion as safe because we expected each new CPU/thread to appear in order. However the -M raspi2 model triggered a case where a new high cpu_index thread started executing just before a smaller one. Clean this up by converting the GArray into the simpler GPtrArray and then holding a lock for the expansion. Signed-off-by: Alex Benn=C3=A9e Cc: Alexandre Iooss Reviewed-by: Richard Henderson Message-Id: <20221027183637.2772968-29-alex.bennee@linaro.org> diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c index 1b3bb7ebba..e255bd21fd 100644 --- a/contrib/plugins/execlog.c +++ b/contrib/plugins/execlog.c @@ -18,11 +18,30 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_version =3D QEMU_PLUGIN_VERSION; =20 /* Store last executed instruction on each vCPU as a GString */ -GArray *last_exec; +static GPtrArray *last_exec; +static GMutex expand_array_lock; =20 static GPtrArray *imatches; static GArray *amatches; =20 +/* + * Expand last_exec array. + * + * As we could have multiple threads trying to do this we need to + * serialise the expansion under a lock. Threads accessing already + * created entries can continue without issue even if the ptr array + * gets reallocated during resize. + */ +static void expand_last_exec(int cpu_index) +{ + g_mutex_lock(&expand_array_lock); + while (cpu_index >=3D last_exec->len) { + GString *s =3D g_string_new(NULL); + g_ptr_array_add(last_exec, s); + } + g_mutex_unlock(&expand_array_lock); +} + /** * Add memory read or write information to current instruction log */ @@ -33,7 +52,7 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_= meminfo_t info, =20 /* Find vCPU in array */ g_assert(cpu_index < last_exec->len); - s =3D g_array_index(last_exec, GString *, cpu_index); + s =3D g_ptr_array_index(last_exec, cpu_index); =20 /* Indicate type of memory access */ if (qemu_plugin_mem_is_store(info)) { @@ -61,11 +80,10 @@ static void vcpu_insn_exec(unsigned int cpu_index, void= *udata) GString *s; =20 /* Find or create vCPU in array */ - while (cpu_index >=3D last_exec->len) { - s =3D g_string_new(NULL); - g_array_append_val(last_exec, s); + if (cpu_index >=3D last_exec->len) { + expand_last_exec(cpu_index); } - s =3D g_array_index(last_exec, GString *, cpu_index); + s =3D g_ptr_array_index(last_exec, cpu_index); =20 /* Print previous instruction in cache */ if (s->len) { @@ -163,7 +181,7 @@ static void plugin_exit(qemu_plugin_id_t id, void *p) guint i; GString *s; for (i =3D 0; i < last_exec->len; i++) { - s =3D g_array_index(last_exec, GString *, i); + s =3D g_ptr_array_index(last_exec, i); if (s->str) { qemu_plugin_outs(s->str); qemu_plugin_outs("\n"); @@ -201,7 +219,11 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin= _id_t id, * Initialize dynamic array to cache vCPU instruction. In user mode * we don't know the size before emulation. */ - last_exec =3D g_array_new(FALSE, FALSE, sizeof(GString *)); + if (info->system_emulation) { + last_exec =3D g_ptr_array_sized_new(info->system.max_vcpus); + } else { + last_exec =3D g_ptr_array_new(); + } =20 for (int i =3D 0; i < argc; i++) { char *opt =3D argv[i]; --=20 2.34.1