xiaoxiang781216 commented on a change in pull request #3050:
URL: https://github.com/apache/incubator-nuttx/pull/3050#discussion_r599597115
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File path: drivers/syslog/syslog_channel.c
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@@ -135,14 +139,82 @@ static int syslog_default_putc(int ch)
int syslog_channel(FAR const struct syslog_channel_s *channel)
{
+#if (CONFIG_SYSLOG_MAX_CHANNELS != 1)
+ int i;
+#endif
+
DEBUGASSERT(channel != NULL);
if (channel != NULL)
{
DEBUGASSERT(channel->sc_putc != NULL && channel->sc_force != NULL);
- g_syslog_channel = channel;
+#if (CONFIG_SYSLOG_MAX_CHANNELS == 1)
+ g_syslog_channel[0] = channel;
return OK;
+#else
+ for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
+ {
+ if (g_syslog_channel[i] == NULL)
+ {
+ g_syslog_channel[i] = channel;
+ return OK;
+ }
+ else if (g_syslog_channel[i] == channel)
+ {
+ return OK;
+ }
+ }
+#endif
+ }
+
+ return -EINVAL;
+}
+
+/****************************************************************************
+ * Name: syslog_channel_remove
+ *
+ * Description:
+ * Removes an already configured SYSLOG channel from the list of used
+ * channels.
+ *
+ * Input Parameters:
+ * channel - Provides the interface to the channel to be removed.
+ *
+ * Returned Value:
+ * Zero (OK) is returned on success. A negated errno value is returned
+ * on any failure.
+ *
+ ****************************************************************************/
+
+int syslog_channel_remove(FAR const struct syslog_channel_s *channel)
Review comment:
> > All methods need be protected by spin lock or critical section.
>
> I just cannot understand how syslog is protected now.
> Following the code from `syslog()` to `nx_vsyslog()`, I don't see any
protection (e.g. semaphore etc).
>
The protection doesn't need before since g_syslog_channel is never changed
at the runtime.
> Shouldn't syslog be thread-safe? In the sense that multiple tasks may log
simultaneously?
Yes, syslog is not only thead-safe but also interrupt safe(true for uart,
ram and lwl, false for file and dev). The protection is done inside the driver
level. syslog/nx_vsyslog use stack variable only except g_syslog_channel, which
need to protect now with your new code.
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