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VFS: Fix bug which occurs when driver is installed during a select() call

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Closes https://github.com/espressif/esp-idf/issues/3554
This commit is contained in:
Roland Dobai 2019-10-14 09:22:55 +02:00
parent 054e2dbb44
commit 5464aaac45
3 changed files with 85 additions and 6 deletions
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8
components/vfs/README.rst
View file

@ -106,6 +106,10 @@ given VFS driver.
:cpp:func:`end_select` is called to stop/deinitialize/free the
environment which was setup by :cpp:func:`start_select`.
.. note::
:cpp:func:`end_select` might be called without a previous :cpp:func:`start_select` call in some rare
circumstances. :cpp:func:`end_select` should fail gracefully if this is the case.
Please refer to the
reference implementation for the UART peripheral in
:component_file:`vfs/vfs_uart.c` and most particularly to the functions
@ -153,6 +157,10 @@ Please see :component_file:`lwip/port/esp32/vfs_lwip.c` for a reference socket d
If you use :cpp:func:`select` for socket file descriptors only then you can enable the
:envvar:`CONFIG_LWIP_USE_ONLY_LWIP_SELECT` option to reduce the code size and improve performance.
.. note::
Don't change the socket driver during an active :cpp:func:`select` call or you might experience some undefined
behavior.
Paths
-----

63
components/vfs/test/test_vfs_select.c
View file

@ -21,6 +21,7 @@
#include "driver/uart.h"
#include "esp_vfs.h"
#include "esp_vfs_dev.h"
#include "esp_vfs_fat.h"
#include "lwip/sockets.h"
#include "lwip/netdb.h"
#include "test_utils.h"
@ -549,3 +550,65 @@ TEST_CASE("concurrent selects work", "[vfs]")
deinit(uart_fd, socket_fd);
close(dummy_socket_fd);
}
TEST_CASE("select() works with concurrent mount", "[vfs][fatfs]")
{
wl_handle_t test_wl_handle;
int uart_fd, socket_fd;
init(&uart_fd, &socket_fd);
const int dummy_socket_fd = open_dummy_socket();
esp_vfs_fat_sdmmc_mount_config_t mount_config = {
.format_if_mount_failed = true,
.max_files = 2
};
// select() will be waiting for a socket & UART and FATFS mount will occur in parallel
struct timeval tv = {
.tv_sec = 1,
.tv_usec = 0,
};
fd_set rdfds;
FD_ZERO(&rdfds);
FD_SET(uart_fd, &rdfds);
FD_SET(dummy_socket_fd, &rdfds);
test_select_task_param_t param = {
.rdfds = &rdfds,
.wrfds = NULL,
.errfds = NULL,
.maxfds = MAX(uart_fd, dummy_socket_fd) + 1,
.tv = &tv,
.select_ret = 0, // expected timeout
.sem = xSemaphoreCreateBinary(),
};
TEST_ASSERT_NOT_NULL(param.sem);
start_select_task(&param);
vTaskDelay(10 / portTICK_PERIOD_MS); //make sure the task has started and waits in select()
TEST_ESP_OK(esp_vfs_fat_spiflash_mount("/spiflash", NULL, &mount_config, &test_wl_handle));
TEST_ASSERT_EQUAL(pdTRUE, xSemaphoreTake(param.sem, 1500 / portTICK_PERIOD_MS));
// select() will be waiting for a socket & UART and FATFS unmount will occur in parallel
FD_ZERO(&rdfds);
FD_SET(uart_fd, &rdfds);
FD_SET(dummy_socket_fd, &rdfds);
start_select_task(&param);
vTaskDelay(10 / portTICK_PERIOD_MS); //make sure the task has started and waits in select()
TEST_ESP_OK(esp_vfs_fat_spiflash_unmount("/spiflash", test_wl_handle));
TEST_ASSERT_EQUAL(pdTRUE, xSemaphoreTake(param.sem, 1500 / portTICK_PERIOD_MS));
vSemaphoreDelete(param.sem);
deinit(uart_fd, socket_fd);
close(dummy_socket_fd);
}

20
components/vfs/vfs.c
View file

@ -877,8 +877,12 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
return -1;
}
// Capture s_vfs_count to a local variable in case a new driver is registered or removed during this actual select()
// call. s_vfs_count cannot be protected with a mutex during a select() call (which can be one without a timeout)
// because that could block the registration of new driver.
const size_t vfs_count = s_vfs_count;
fds_triple_t *vfs_fds_triple;
if ((vfs_fds_triple = calloc(s_vfs_count, sizeof(fds_triple_t))) == NULL) {
if ((vfs_fds_triple = calloc(vfs_count, sizeof(fds_triple_t))) == NULL) {
__errno_r(r) = ENOMEM;
ESP_LOGD(TAG, "calloc is unsuccessful");
return -1;
@ -952,7 +956,7 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
}
}
void **driver_args = calloc(s_vfs_count, sizeof(void *));
void **driver_args = calloc(vfs_count, sizeof(void *));
if (driver_args == NULL) {
free(vfs_fds_triple);
@ -961,7 +965,7 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
return -1;
}
for (int i = 0; i < s_vfs_count; ++i) {
for (int i = 0; i < vfs_count; ++i) {
const vfs_entry_t *vfs = get_vfs_for_index(i);
fds_triple_t *item = &vfs_fds_triple[i];
@ -977,7 +981,7 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
if (err != ESP_OK) {
call_end_selects(i, vfs_fds_triple, driver_args);
(void) set_global_fd_sets(vfs_fds_triple, s_vfs_count, readfds, writefds, errorfds);
(void) set_global_fd_sets(vfs_fds_triple, vfs_count, readfds, writefds, errorfds);
if (sel_sem.is_sem_local && sel_sem.sem) {
vSemaphoreDelete(sel_sem.sem);
sel_sem.sem = NULL;
@ -1022,9 +1026,9 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
xSemaphoreTake(sel_sem.sem, ticks_to_wait);
}
call_end_selects(s_vfs_count, vfs_fds_triple, driver_args); // for VFSs for start_select was called before
call_end_selects(vfs_count, vfs_fds_triple, driver_args); // for VFSs for start_select was called before
if (ret >= 0) {
ret += set_global_fd_sets(vfs_fds_triple, s_vfs_count, readfds, writefds, errorfds);
ret += set_global_fd_sets(vfs_fds_triple, vfs_count, readfds, writefds, errorfds);
}
if (sel_sem.is_sem_local && sel_sem.sem) {
vSemaphoreDelete(sel_sem.sem);
@ -1049,6 +1053,8 @@ void esp_vfs_select_triggered(esp_vfs_select_sem_t sem)
// which has a permanent FD. But in order to avoid to lock
// s_fd_table_lock we go through the VFS table.
for (int i = 0; i < s_vfs_count; ++i) {
// Note: s_vfs_count could have changed since the start of vfs_select() call. However, that change doesn't
// matter here stop_socket_select() will be called for only valid VFS drivers.
const vfs_entry_t *vfs = s_vfs[i];
if (vfs != NULL && vfs->vfs.stop_socket_select != NULL) {
vfs->vfs.stop_socket_select(sem.sem);
@ -1067,6 +1073,8 @@ void esp_vfs_select_triggered_isr(esp_vfs_select_sem_t sem, BaseType_t *woken)
// which has a permanent FD. But in order to avoid to lock
// s_fd_table_lock we go through the VFS table.
for (int i = 0; i < s_vfs_count; ++i) {
// Note: s_vfs_count could have changed since the start of vfs_select() call. However, that change doesn't
// matter here stop_socket_select() will be called for only valid VFS drivers.
const vfs_entry_t *vfs = s_vfs[i];
if (vfs != NULL && vfs->vfs.stop_socket_select_isr != NULL) {
vfs->vfs.stop_socket_select_isr(sem.sem, woken);