Fix broken kernel tracing in presence of offline CPUs #1849
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shoffmeister
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With the PR merged, will produce kernel trace output (note the hard-coded path to libmcount, I am running this from the build environment) |
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utils/kernel.c
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| @@ -615,10 +615,10 @@ int record_kernel_trace_pipe(struct uftrace_kernel_writer *kernel, int cpu, int | |||
| if (n < 0) { | |||
| if (errno == EINTR) | |||
| goto retry; | |||
| if (errno == EAGAIN) | |||
| if ((errno == EAGAIN) || (errno == ENODEV)) | |||
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@shoffmeister @honggyukim
There is no need (and it's not usual) to add the extra braces around == because it precedence and order of evaluation comes before the logical or ||:
| if ((errno == EAGAIN) || (errno == ENODEV)) | |
| if (errno == EAGAIN || errno == ENODEV) |
A detailed reference: https://learn.microsoft.com/en-us/cpp/c-language/precedence-and-order-of-evaluation?view=msvc-170
Otherwise, LGTM.
If @shoffmeister did not deny maintainer write access, uftrace maintainers should be able to apply my suggestion by clicking the button "commit suggestion".
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Oh, cool. I didn't notice this feature. Yes I prefer no parenthesis.
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Removed the redundant brackets and force pushed for a simple commit history.
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It looks the brackets are still there. Please check again.
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Indeed, sorry + fixed!
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Offline CPUs may be encountered in a number of scenarios, for instance in the presence of virtualization through VMware Workstation, where the product advertises 128 CPUs as present, but then only makes a (configurable) subset of these available and online for use. Signed-off-by: Stefan Hoffmeister <stefan.hoffmeister@econos.de>
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Offline CPUs may be encountered in a number of scenarios, for instance in the presence of virtualization through VMware Workstation, where the product advertises 128 CPUs as present, but then only makes a (configurable) subset of these available and online for use.
Fixes #1846